Royal Bociety. 385 



The President and Council refer to the documents which have 

 been submitted to them, and more especially to the "Explanations 

 and Sailing Directions to accompany wind and current charts " j^re- 

 pared by Lieutenant Maury, for a more detailed account of this 

 system of cooperative observations, and of the grounds ujjon which 

 they have ventured to make the preceding recommendations. 



(Signed) S. Hunter Christie, Sec. R.S. 



H. U. Addington, Esq. 



" Second Appendix to a paper entitled ' Discovery that the 

 Veins of the Bat's Wing (which are furnished with valves) are en- 

 dowed with rvthmical contractility.' " By T. Wharton Jones, Esq., 

 F.R.S. &c. 



The author states that, from a microscopical examination of tlie 

 blood-vessels and circulation in the ears of the long-eared bat, he 

 has ascertained that, different from what he had discovered to be the 

 case in the wings, the veins of the ears are unfurnished with valves, 

 and are not endowed with rythmical contractility, and that the 

 onward flow of blood in them is consequently uniform. 



May 27. — The reading of Mr. Huxley's paper, " Upon the Mor- 

 phology of the Cephalous Mollusca, as illustrated by the Anatomy 

 of certain Heteropoda and Pteropoda," commenced at the last meet- 

 ing, was resumed and concluded. 



In the present memoir the author endeavours to determine, upon 

 anatomical and embryological grounds, the true homologies of the 

 different organs of the Cephalous TvIoUusca, and thence to arrive at 

 some idea of the archetypal form, as definite modifications of which 

 the existing molluscous forms may be considered to have arisen. 



Tlie Pelagic Heteropoda and Pteropoda, from their small size and 

 extreme transparency, are peculiarly favourable subjects for the ana- 

 tomical part of this investigation, and it is from a detailed examina- 

 tion of those systems of organs which are of importance for the pur- 

 pose that the author deduces the following conclusions : — 



1. In the Heteropoda the intestine is bent towards the dorsal or 

 hcemal side in consequence of the development behind the anus of 

 the visceral "hernia," M'hich is therefore called a 2}ost-abdojne?t. 



2. In the Heteropoda, the " foot," in its most perfect condition, 

 consists of three portions, n propodium, niesopodium and metapodium. 



3. The Heteropoda are more or less prosobranchiate, the degi'ee 

 depending upon the amount of development of the post- abdomen. 



4. In the Pteropoda the intestine is bent towards the ventral or 

 neural side, in consequence of the develo])ment of the visceral " her- 

 nia" in front of the anus. It is therefore called an abdomen. 



5. In the Pteropoda, the foot, besides the parts mentioned above, 

 possesses an additional api)endage, the epipodium, which forms the 

 expanded wing characteristic of the group. 



(J. The Pteropoda are opisthobranchiate, prosobranchiate, or in- 

 termediate in character, according to the degree of development of 

 the abdomen. 



Phil. May. S. 4. Vol. 4. No. 20. Nov. 1852. 2 C 



