GALEOMMA. 107 



Animal white, thick, shaped like the shell, but larger 

 than it. The mantle is greatly developed, and closed in 

 front ; it has a thickened, furbelowed double border, the 

 outer part lining the margin of the shell, and furnished with 

 a series of rounded distant tubercles, the central ones 

 largest, all placed at regular distances, and of a brilliant 

 white-frosted aspect. There are nine or ten on each side, 

 the intervals between them furnished with a fringe of fine 

 short white triangular filaments. Both observers quoted 

 compare the tubercular bodies to the so-called eyes of 

 Pecten. Anteriorly the mantle is open for the passage of 

 a long, cylindrical, very extensile foot, furnished with a 

 byssiferous organ at its base : its margins pout out beyond 

 the shell in a lip-like manner. Above the mouth is a short 

 tube, apparently imperforate, and furnished at its extre- 

 mity with a small process, reminding us of the organ at 

 the anterior end of Lepton. Posteriorly it forms two short 

 tubes, an upper and small one, which is the anal one, and 

 a lower and larger branchial siphon, the former with even, 

 the latter with sinuated margins to its orifice. There are 

 a pair of branchial leaflets on each side, and also a pair of 

 labial leaflets, more coarsely pectinated than the branchial. 



Mr. Clark states that it adheres so strongly by means 

 of its byssus, as, when the animal was taken, to require 

 some force to detach it from the rock. " During twenty- 

 four hours," he states, " we kept it alive in a saucer, and 

 three or four diiferent times it spun a byssus, once de- 

 taching itself and leaving the threads behind, crawling to a 

 short distance and then again attaching itself. We had 

 the good fortune to witness the operation. From the slit 

 at the root of the foot a light green glutinous matter was 

 poured out with such rapidity, that in less than five 

 minutes the animal was fixed. When detached it opened 



