KOBSON : ON VIVIPARITY IN LlMICOLAItlA. 33 



Transference from a tropical climate to that of England may well 

 have caused a normally ovoviviparous or oviparous animal to become 

 viviparous. I believe a similar result was achieved (artificially) by 

 Kiinimerer (4), who has changed the mode of reproduction in 

 Salamandra by alteration of the environmental conditions. TTii- 

 fortuiiately I have not been able to verify the facts of this experiment, 

 but I believe S. maculosa ordinarily keeps its embryos a short time 

 in the uterus, and eventually they are hatched out as larvae. If, 

 however, the temperature is lowered, the ova remain a longer time in 

 the uterus, and the larval stages are suppressed. 



I have mentioned tlie fact that tlie eggs which were found in 

 L. SmitJn were perforated, and a good part of their contents absent. 

 In addition several of the young in the new species had holes in their 

 shells, and the integument of the foot and mantle seemed to be frayed 

 and torn. It suggests itself to me that we have here a case of inter- 

 uterine cannibalism, in which, owing to the inability of the young to 

 obtain food as the result of their delayed delivery from the parental 

 uterus, they were forced to obtain their supply of food and calcareous 

 matter from each other. Such a phenomenon undoubtedly does occur 

 as a natural process among Mollusca. Cases are known among the 

 Streptoneura in which the embryos devour one another and have 

 developed as a consequence larval excretory organs. An especially 

 interesting case is recoided by Glaser (5) in his account of the 

 development of Fasciolaria. I am indebted to Dr. Jenkinson, 

 lecturer in Embryology in the University of Oxford, for reminding me 

 of this instance. The difference between it and the phenomena under 

 consideration in this paper is of course that in Fasciolaria it is of 

 regular occurrence and constitutes part of the necessary events of 

 ontogeny, while in Limicolaria I presume it to be exceptional in its 

 occurrence. Lastly, as a point of detail, in Fasciolaria the cannibal 

 embryos and their victims are all within the same capsule, which is 

 not the case in Limicolaria. 



Bibliography. 



1. Semper, Sitzb. Phys. Med. Ges. Wurzburg, 1886. 



2. Gibbons, Journal of Conchology, vol. ii, p. 143. 



3. Pelseneer, Mollusca (Lankester's Treatise), p. 131. 



4. Kamnierer, Archiv. Entw. Mechanik, vols, xvii, xxii. 



5. Glaser, Biological Bulletin, vol. x. 



VOL. X. — MARCH, 1912. 



