32 SUMMARY OF CURRENT RESEARCHES RELATING TO 



structure of the arteries, veins, heart, and branchial hearts ; and the 

 capillary system in particular. The wide distribution of the capillary 

 vessels, the presence of an endothelium around every blood-containing 

 cavity, except possibly the hearts, and the absence of demonstrable 

 lacunae, all lead to the conclusion that the arterial and venous vessels of 

 the squid are connected by capillaries, so that the vascular system is 

 closed. 



y. Gasteropoda. 



Notes on Species of Fulgur.* — B. Smith communicates some pre- 

 liminary results of a phylogenetic study of the species of Fulgur. The 

 changes in ornamentation agree in general with those noted by the 

 Countess von Linden in regard to other Gasteropods. A plausible 

 pedigree is sketched. 



The author describes an abnormal specimen of F. caniculatum, 

 apparently due to accident when the shell was young ; and he records 

 a series of F. carica, in which there was some degree of sexual 

 dimorphism, since the adult males were all smaller than the adult 

 females. 



Recent Researches on Gasteropods.f — H. Simroth gives a valuable 

 account of recent researches on the structure, relationships, and cecology 

 of Gasteropods. He discusses Kowalevsky's studies on two minute 

 species of Chaztoderma from the Sea of Marmora ; Thiele's conclusion 

 that Molluscs have only a haemoccel ; the interesting work of Stempell 

 and of Biedermann on the nature and origin of the shell ; Thiele's 

 theory of Gasteropod torsion ; Guiart's system of Gasteropods ; the 

 work of Woodward and others on Pleurotomaria ; Bonnevie's account 

 of the parasitic Enter oxenos g. n. ; Jordan's account of the locomotion 

 of Aplgsia ; Guiart's study of Opisthobranchs ; Kowalevsky's descrip- 

 tion of the striking form Pseudovermis paradoxus ; Pelseneer's studies 

 on Pulmonates ; and many other researches, about fifty in all. 



Sex Determination of Gametes in Hermaphrodite Gonads. $ — 

 P. Ancel maintains, with particular reference to Helix pomatia, that the 

 sex-cells are at first indifferent, that those which appear before the 

 nutritive elements become male cells (giving origin to spermatozoa), and 

 that those which appear after the nutritive elements become ova. He 

 thinks this conclusion may be extended to similar cases; the "cy to- 

 sexual " character of the gametes is determined by the time of their 

 appearance in relation to the appearance of the nutritive cells. 



Opisthobranchs from Gulf of Siam.§ — R. Bergh reports on a col- 

 lection made by Th. Mortensen on the Danish expedition to Siam 

 (1900). It includes three new Tectibranchs : — Aplysia immunda, 

 Aphjsiella incerta, and Aclesia oceUigera ; and five new Nudibranchs :— 

 Tdalia plebeia, Doriopsilla pallida, Marionia cJiloant/ies, Melibe bvcephala, 

 and Nossis indica. 



* Proc. Acad. Nat. Sci. Philadelphia, 1902, pp. 505-7. 



+ Zool. Centralbl., ix. (1902) pp. 265-305 (4 figs.). 



X Arch. Zool. Expe>., x. (1902) Notes et Revue, pp. Ixxxiv.-xciv. 



§ Mem. Acad. Daneinark, Copenhagen, xii. (1902) pp. 155-218 (3 pla. and 1 map). 



