CORBULA. 149 



CORBULA, Bruguiere. 

 C. NUCLEUS, Lamarck. 

 C. nucleus, Brit. Moll/i. p. 181, pi. 9. f. 7-12; (animal) pi. G. f. 3. 



Animal subtriangular, thick, yellowish- white ; mantle closed, 

 except anteriorly, presenting an orifice having its circumference 

 finely dentated, that marks the point of passage of a moderately 

 long, subcylindrical byssal foot ; posteally it forms two short 

 united siphons, each with 8-10 cirrhi ; the upper, or anal, has 

 a hyaline, tubular, retractile, valvular, globular membrane, 

 which is in frequent action, and appears to regulate the pro- 

 pulsion of the faecal matters, and the ingress and egress of the 

 water for the various purposes of the animal oeconomy, which 

 will be fully explained in the observations on the Pholadidce. 



On each side of the body there is a pair of very unequal 

 branchiae, which hang obliquely, the upper being narrow, the 

 lower larger and more triangular ; their colour brown, smooth 

 on their outsides, and finely striated within ; on each side there 

 are two long, narrow, pointed, brown pendulous palpi, pectinated 

 strongly on both surfaces. Besides the red points circling the 

 cirrhi of the siphonal tubes, there is a dark line encompassing 

 both at a short distance from the cirrhal circle of points ; these 

 are better seen in the dead animal. The liver is black-green. 



We have taken, in the deepest part of the British Channel, 

 conglomerations of many thousands of this species of all 

 growths, having shells of brown and white, and often roseate 

 hues ; they adhere to each other by fine silky byssal filaments. 



The C. ovata is a doubtful British species, and Mr. Wai- 

 pole, of Monkstown, Co. Dublin, having favoured us with a 

 specimen of his C. rosea, we can only consider it the common 

 roseate variety of C. nucleus. Since the above remark, Mr. 

 Walpole has informed us, that he has submitted specimens to 

 Professor Forbes, who has come to the same conclusion. 

 As to the C. ovata and C. rosea of the ' British Mollusca/ 

 we supply the following references : 



C. ROSEA, Brown. 



C. rosea ? Brit. Moll. i. p. 185, pi. 9. f. 13, 14. 



C. OVATA, Forbes. 



C. ovata? Brit. Moll. i. p. 187, pi. 9. f. 15. 



