Invertebrate Gallery of the Indian Museum. 65 



The Macrurous Decapods form a large sub-Order, most 

 of the members of which are marine, though a consider- 

 able number inhabit rivers and other fresh-waters. 



The marine forms are found in every kind of region, 

 from the Arctic shores to those of the Equator, from tide- 

 mark to the deepest abysses, from creeks and backwaters 

 to the open expanses of the ocean ; and they are found in 

 all situations, burrowing in the sand and mud, hiding in 

 crevices in rocks and under stones, sheltering amid branch- 

 ing colonies of the Sea-firs, Sea-mats, etc., flitting near the 

 surface of the ocean, or swarming near the bottom. 



Of the numerous tribes and families into which the 

 Decapod Macrura are subdivided, the following are re- 

 presented in the Gallery : — 



1st Tribe, Thalassinidea, Case 41. — Two families are re- 

 presented, the Thalassiniclx and the Callianassida;. 



The Thalasslnidse include the single genus Thalassina, 

 one of the few species of which, Thalassina scorpionoides, 

 is common in Indian estuaries, where it lives in deep 

 burrows tunnelled in the mud. Observe the long narrow 

 tail already beginning to show signs of degeneration, and 

 the small degenerated eyes. 



The Callianassidse are small burrowing Crustaceans 

 found in the sand usually between tide-marks, but often 

 at great depths. Specimens of Callianassa, Callianidea 

 Gebia, and Gebiopsis are shown in the Gallery, all of them 

 having been taken in Indian waters. In both of these 

 families the carapace is short and the *' tail " long, and 

 the pincers of the thoracic legs are imperfectly developed, 

 forming '' subchelae." 



2nd Tribe, Scyllaridea or Loricata, Cases 41 and 53. 



This tribe includes two families, the Scyllarida; and the 

 Palinurid.v, both of which are represented in the Gallery. 



The Scyllaridse have a broad flattened crab-like cara- 

 pace, and the antennae (second pair) form flat warty plates. 

 None of the thoracic legs are in the form of pincers or 



