Mr. W. Clark on the Animal of Kellia rubra. 145 



to supply moisture to prevent the desiccation of the branchise of 

 Kellia rubra, as well as those of the Littorina jugosa and petraa, 

 and of the Patellce and Mytili, which, in many situations, are not 

 submerged throughout the year; and I can affirm that I saw 

 hundreds of some of the animals I have named from ten to twenty 

 feet above the level of the highest spring-tide at any period of 

 the year. How these animals exist is a mystery ; it is possible the 

 saline particles in the air, and the fine spray carried by the winds 

 to the rocks on which these animals are found, may supply suffi- 

 cient moisture for the branchise ; but can the animal from these 

 materials extract sustentation ? There is no appearance of their 

 descent to lower levels ; they appear to be fixtures ; and I am in- 

 formed they are to be found in the same situation in all seasons. 

 As for Kellia rubra, they exist in myriads in all the higher levels 

 of the littoral zone, but in the very lowest they are not submerged 

 for four hours during the twenty-four. 



These facts invalidate the doctrine of the branchial currents by 

 cilia, and their having separate apertures of ingress and egress ; 

 for what can be the use of them in Kellia rubra, when they neces- 

 sarily must be interrupted for twenty hours out of the twenty- 

 four throughout the year ? It seems strange, according to Mr. 

 Alder, that a special branchial organ should be furnished by na- 

 ture for a bivalve, which can better dispense with such a specialty 

 than any other in existence. 



With my best thanks for your liberal insertion of my papers 

 in the ' Annals,' 



I remain, Gentlemen, your most obedient servant, 



William Clark. 



Postscript. — To corroborate the conjecture stated above of 

 the real uses of the anterior tubes of Kellia rubra and Kellia sub- 

 orbicularis, I beg to add, that I have just examined a fine Kellia 

 suborbicularis. I placed it on the umbones ; it immediately ex- 

 serted and opened the tube, and by the aid of a powerful lens I 

 counted at its fundus fifteen largely developed ova, and I have 

 not the slightest doubt that these anomalous animals, as regards 

 reproduction, are furnished with these anomalous tubes to minister 

 thereto; and I have further to state, that on submitting this ani- 

 mal to my scalpel and to one of Mr. Ross's best microscopes, I 

 received the fullest confirmation of my conjectures, having found 

 at the bottom of the ovarium resting on the fundus of the tube, 

 ova in all states of development and fully-formed testaceous young. 

 I have carefully preserved the shell and ovarium. Therefore 

 Kellia rubra and Kellia suborbicularis are undoubtedly vivipa- 

 rous ; the only difference between the two is, that the young in 

 Kellia rubra are fully developed in the ovarium, and only require 

 the open tube-like fold for an oviduct, and to convey water to 



Ann. ^ Mag. N. Hist. Ser. 2. Vol. iv. 10 



