66 A Guide to the Zoological Collections in the 



chelae, but all end in simple claws. Three genera are met 

 with in Indian Seas — Scyllarus, Themis, and Ibacus, 

 specimens of all of which are to be seen in Cases 41 

 and 53. 



The Paiinuridae much resemble Lobsters at first sight, 

 but they differ from the Lobster in not having chelae, — all 

 the thoracic legs ending in simple claws. One genus, or 

 subgenus, Panulirus is very common in Indian Seas, off 

 rocky coasts, and in the neighbourhood of coral islands. 

 Notice the specimen of Palinnrus {Panulirus) ornatus 

 with one side of the carapace removed to display the gills, 

 (Case 54). 



3rd Tribe, Astacidea, Case 40. — This tribe includes the 

 Lobsters, and contains four families, all of which are re- 

 presented in the Gallery, though only two, the Eryontidx 

 and Nephropsidx, are to be met with in Indian Seas. 



The recent Eryontidae are entirely confined to the great 

 depths of the sea : the carapace is depressed, and in cor- 

 relation with the fact that they live at great depths to which' 

 sunlight cannot penetrate, the eyes are rudimentary or 

 absent : except in the males of one genus all the thoracic 

 legs end in chelae. In the Indian Seas the Eryontidx ap- 

 pear to be fairly common at depths of from 500 to 1,500 

 fathoms. Specimens of three genera Polycheles, Penta- 

 cheleSy and Willemcesia, are exhibited, all of which were 

 dredged by the officers of the Indian Marine Survey. 



The Nephropsidae or Lobsters proper, are, as far as the 

 Indian fauna is concerned, to be found only in deep water 

 (175 to 250 fathoms), although in other regions they occur 

 in shallow water. The Indian genera are Nephrops and 

 NephropsiSy fine specimens of which are exhibited along 

 with Lobsters from the European and Japan Seas. In 

 Nephrops the eyes are of enormous size, while in Nephr op- 

 sis they are the merest rudiments. This contrast illus- 

 trates the fact that when animals live at moderate depths 

 to which a certain amount of sunlight can penetrate, their 

 eyes often become increased in size to profit by all the 



