414 Miscellaneous, 



ectoderm lying in the naedian longitudinal axis, from which, 

 according to Sarasin, the pedal, intestinal, and visceral ganglia pro- 

 ceed, and which lie homologizes with the ventral nerve-cord of the 

 Annelids. 



In opposition to Sarasin I must lay stress upon the following 

 points. There is in Biitliinia a separate mesoderm, which arises 

 from the endoderra, and the development of which from the two 

 IJrimitive cells is traceable step by step. The archenteron proceeds 

 from an invagination of the endoderm. The whole mid-gut, i. e. 

 stomach and liver, as well as end-gut (if we can use the term at all 

 as applied to mollusks), arises from the archenteron, which always 

 exhibits a distinct lumen. The mouth proceeds directly from the 

 blastopore, accompanied by an invagination of the ectoderm, whicli 

 forms the oesopliagus ; consequently a complete closure of the blas- 

 topore does not take place. The anal opening corresponds to a small 

 ])it at the hinder end of the blastoporal groove. Primitive kidney 

 and kidney, apart from their ectodermic excretory ducts, are of 

 mesodermic origin ; the same is true for the heart and pericardium. 

 The ganglia arise completely separate from one another, and do not 

 come into connexion until afterwards. — Zoolofjischer Anztvjer, 

 siv. Jahrg., 1891, no. 376, pp. 385-388. 



On certain Hejrroductive Phenomena in Cirrhipedes. 

 By M. A. GErvEL. 



The history of the preliminary phenomena of fcrtibzation in the 

 Cirrhipedes is little known. Darwin, relying on the anatomical 

 characters (length of the penis) and on the observation that the ova 

 are not ripe at the same time as the spermatozoa, concluded that 

 reciprocal fertilization must take place, but never actually witnessed 

 it. I was fortunate enough, during my stay at the seaside *, to 

 make a few interesting observations on this subject. 



I had in a tank of the aquarium several specimens of BaJanns (B. 

 tintinnabidum) which had been living for some time and were adult ; 

 my attention was attracted by the very peculiar movements of one 

 of them. 



The movements of the cirri were accelerated, then all at once the 

 latter stopped, opened behind, and from the midst of them there 

 arose a sort of very mobile tentacle, which was moved to the right, 

 to the left, backwards, and in every direction, as if seeking for 

 something: this was the penis. Soon a contraction set in and 

 emission took place ; the penis then resumed its position between 

 the cirri, which also resumed their ordinary movements, until the 

 occuri'cnce of a fresh series of similar phenomena. 



My attention once directed to this point, I was not long in dis- 

 covering analogous phenomena in Lepas anatifira. 



Individuals of the latter species embrace one another to a certain 

 extent with their cirri. It frequently happens that the fertilized 



* These investigations were carried out at M. de I^acazi^Duthiers' 

 laboratory of experimental zoology at Roscoff during the months of 

 August and September, 1891. 



