HABITS OF CRUSTACEANS. 403 



Where one of the mouths of the Sarawak disembogues 

 into the sea, at low water, there is a very extensive mud- 

 flat, the entire surface of which is perforated in every 

 part by a hitherto undescribed species of Gebia, which 

 hides in a perpendicular position, in a superficial burrow, 

 with the extremities of the chelae at the orifice for the 

 purpose of securing whatever prey may offer. Thousands 

 of Macrophthalmi and other crabs live in the same spot, 

 with a small species of Lingula ; while upon the slimy 

 surface, crawl thousands of little brown Cylichna, several 

 Mangelite, and Columbetta. 



The Spheromas are generally obtained in company with 

 Cymodocete, CassidincB, Amplioroidete and others, among 

 dense masses of floating Sea-weed, where they appear to 

 live an active predatory life among the populous mazes of 

 their small, floating forest. They are constantly spinning 

 and darting about, rolling up their bodies into a ball, 

 then straightening them, and crawling among the Algae 

 and Keratophytes, with a great deal of vivacity. Among 

 the collection brought home in the Samarang, are several 

 species not before known to Crustaceologists. 



The very handsome genus Sicyonia of Edwards, swims 

 in a slow and deliberate manner forwards, and occasion- 

 ally with a sudden jerk propels itself vigorously, in a 

 backward direction. It keeps at a considerable distance 

 from the shore, and appears to love deep, still water, 

 never appearing when the sea is at all ruffled. The 

 species obtained by us is new, and is deposited, with the 

 other Crustaceans, in the British Museum. 



Like the genera Thenus and Ibacus, the Scyttants lives 

 at some distance from the shore, and in tolerably deep 



2 i) -2 



