536 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XVI. 



two sub-families distinguished by the presence or absence of a pit in the 

 side of the face between the eye and nostril, a trait in the physiognomy 

 too conspicuous to overlook, though the casual observer may mistake 

 it for the nostril, which latter should be sought for as a minute orifice 

 on the side of the snout in advance of the pit. This opening is called 

 the loreal pit owing to its being located in that region which in birds 

 and other creatures is called the lore. It leads into a blind rounded 

 chamber in the maxillary, and is lined with the same covering which 

 overlies the scales on the face, so that when the creature sheds its skin, 

 a perfect cast of the chamber is thrown off with the slough. Its function 

 has not yet been determined. 



Vipers having no such pit are classed under a separate sub-family, 

 Viperince, and may be called pitless vipers in contradistinction to the 

 Crotalince or pit vipers. This latter sub-family derives its name from the 

 Greek word " krotalon," a rattle, its prototypes being the world-renowned 

 rattlesnakes of the American continent. It comprises four genera, two 

 of which are peculiar to America, and two, Lachesis and Ancistrodon, 

 though not peculiar to, are well represented in India and its dependencies. 

 Lachesis, to which our first snake belongs, is separated from Ancistrodon 

 by having on the head mainly small shields similar to ihose on the 

 creature's back. 



THE COMMON GREEN PIT VIPER. 

 Lachesis gramineus. 1 



The genus Lachesis is a large one comprising forty-one known species 

 which inhabit Asia and America. — Of these eighteen are peculiar to 

 Asia, and ten some within our Indian limits. 



Nomenclature (a) Scientific. Lachesis, from whom the generic name 

 originated, was one of the Parcae or Fates of Grecian mythology who 

 with Clotho and Atropos controlled man's destiny. Our readers who are 

 conversant with ophiology may be more familiar with the genus under 

 its older title Trimeresiirus,'* 



* Thi- name was introduced by Lace'pede. He divided land snakes into thr<e groups, 

 according to the arrangement of the shields beneath the tail, In some these pass uninter- 

 ruptedly from side to side exactly like those on the belly. In the majority of snakes, how- 

 ever, they are divided in the median line by oblique alternately directed sutures so as to form 

 a zigzag line. Earely it happens that some of the first and some of the last shields are 

 divided, whilst some intervening ones are undivided. To ih ; s category he applied the name 

 trimeresurus from the G reek words " treis" three, "meros" part, "aura" tail. The name 

 once created was perpetuated, and as time went on, and snakes « ere classified differently, 

 it became applied t'< this genus to which it is quite inappropriate, for the shields beneath 

 the tail are divided throughout. 



