herpetology n.
a branch of zoology dealing with reptiles and amphibians
Etymology : Greek herpeton quadruped, reptile, from neuter of herpetos crawling, from herpein
Date : 1824 [MWCD]

Herpetology is the branch of zoology concerned with the study of amphibians (including frogs, toads, salamanders, newts, and gymnophiona) and reptiles (including snakes, lizards, amphisbaenids, turtles, terrapins, tortoises, crocodilians, and the tuataras). Batrachology is a further subdiscipline of herpetology concerned with the study of amphibians alone. […] The word “herpetology” is from Greek: ἑρπετόν, herpeton, “creeping animal” and -λογία, -logia. People with an avid interest in herpetology and who keep different reptiles or amphibians often refer to themselves as “herpers”. [Wikipedia: Herpetology]

Herpetology is the study of amphibians and reptiles. Living amphibians and reptiles are representatives of a small number of the many historical tetrapod radiations (Table 1.1; Fig. 1.1). Amphibians were the first truly terrestrial vertebrates. Their ancestors were lobe-finned fishes (Sarcopterygii), a group of bony fishes (Osteichtyes). These fishes appeared in the Devonian Period (more than 380 million years before present [mybp]) and radiated in fresh and salt water. The earliest fossils assigned to Tetrapoda (from Greek, tetra = four, poda = foot) included Acanthostega and Ichthyostega, both of which were completely aquatic but had four distinct limbs. They appeared in the late Devonian (about 360 mybp) and are in a group of tetrapods referred to as ichthyostegalians (Fig. 1.1). Amphibians have successfully exploited most terrestrial environments while remaining closely tied to water or moist microhabitats for reproduction. Most amphibians experience rapid desiccation in dry environments, but some species have evolved spectacular adaptations that permit existence in extreme habitats.

During the Carboniferous, about 320 mybp, the anthracosaurs appeared (Fig. 1.1). They not only were able to reproduce on land in the absence of water but also had an effective skin barrier that presumably reduced rapid and excessive water loss. Extant reptiles (including birds) and mammals descended from anthracosaurs. The study of birds and mammals, formally called Ornithology and Mammalogy, respectively, are beyond the scope of this book.

Amphibians and reptiles (collectively, herps) are not each other’s closest relatives evolutionarily, yet they have traditionally been treated as though they are related (e.g., “herpetology” does not include birds and mammals). […]

Laurie J. Vitt and Janalee P. Caldwell, Herpetology : An Introductory Biology of Amphibians and Reptiles, 3rd ed., Academic Press, 2009, p.3.

※ 英和辞書には、herpetology の訳として「爬虫類学」とのみ書かれたものもあるが、herpetology は爬虫類と両生類の両方を扱う学問なので、正確さに欠ける。この「爬虫類と両生類の両方を扱う学問」のことを日本語でなんというかというと、この両方を一語で表す日本語の単語はないようで、「The Herpetological Society of Japan」は「日本爬虫両棲類学会」である。

※ 語源から見ると、herpetology の herpeto- はギリシャ語 herpeton（這うもの）に由来。これに対し、reptile（爬虫類）はラテン語起源。

reptile n.
Etymology: Middle English reptil, from Middle French or Late Latin; Middle French reptile (fem.), from Late Latin reptile (neut.), from neuter of reptilis creeping, from Latin reptus, past participle of repere to crawl; akin to Lithuanian rėplioti to crawl [MWCD]

※ 爬虫類と両生類をいっしょに扱うのは、古くからの伝統で、リンネは爬虫類と両生類を異なるものとして区分しなかった。

“Herp” is a vernacular term for reptiles and amphibians. It is derived from the old term “herpetile”, with roots back to Linnaeus’ classification of animals, in which he grouped reptiles and amphibians together in the same class. There are over 6700 species of amphibians and over 9000 species of reptiles. In spite of its modern taxonomic irrelevance, the term has persisted, particularly in the names of herpetology, the scientific study of reptiles and amphibians, and herpetoculture, the captive care and breeding of reptiles and amphibians. [Wikipedia: Herpetology]

※ 両生類のみを扱う学問の名称として、batrachology という語がある。