222 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



Auuulata. 



Vitelline Membrane of Serpulids.* — A. Soulier finds that this 

 membrane persists in Serpula crater on to the trochophore stage, having 

 a protective role throughout. The posterior end of the trochophore 

 breaks through, and the membrane gradually disappears from behind 

 forwards. The same persistence and disappearance is to be seen in 

 Hydroides pectinata and Protula meilhaci. 



Polychsetsof Falkland Islands, f — Pierre Fauvel reports on a collec- 

 tion, mostly littoral, made by Eupert Vallentin. It is interesting to find 

 the same species occurring in regions so far separate as Norway and 

 Tierra del Fuego, the Arctic Ocean and the shore of the Antarctic Con- 

 tinent. Far over sixty species occur in both hemispheres. Temperature 

 is an important factor in determining the distribution. Many species are 

 cosmopolitan, and it is important to compare these so as to eliminate in- 

 dividual variations or modifications. Claparede has criticized some of 

 de Quatrefages' " varietes alcooliques." 



Structure and Reproduction of Naidomorpha. — Lucienne Dehorne 

 has made a careful study of Ghsetogaster diaphanus and Stylaria lacustris, 

 two typical Naidomorph Oligochsets. The epidermis shows highly 

 diflPerentiated tactile cells. The basal prolongation of each traverses 

 the musculature and comes into relation with one of the bipolar cells of 

 an intermediate ganglion, which brings it into relation with the multi- 

 polar cells of the nerve-centres. These sensory elements are most 

 abundant on the cephalic lobe, but occur isolated all over the body. 



The swelling of the mid-gut, sometimes called stomach, has an intra- 

 epithelial reticulum which may be branchial in function. There is a 

 complex intra-epithelial vascular system on the intestine. The chlo- 

 ragogen investment is separated from the intestine by the basal 

 memt)rane, a lacunar blood system, and the intestinal muscles. The 

 chloragosomes seem to be excretory digestive products forced into the 

 blood. The nerve-chain has no neurochord. Each cerebroid mass in 

 GhsetogaMer has a sensory organ embedded in a mass of ganglion cells. 

 The " chitinoid platelet " of Vejdovsky consists of two or three flat- 

 tened ganglion cells, forming a cap on the median lobe of the brain. 

 The epithelial eyes of Stylaria are fully described. All the Naido- 

 morphs become sexual at a particular season, and all show the same 

 complex reproductive system. 



The zones of scissiparity are always situated in a particular segment, 

 behind the septum. Besides the normal scissiparity seen by itself in 

 Dero and Ophidonais, there is in all the others a second mode, a pre- 

 cocious scissiparity, and this diJBFers in Nais and Stylaria types. It is the 



* Arch. Zool. Exper., Ivi. (1916) Notes et Revue, No. 1, pp. 16-20 (3 figs.), 

 t Arch. Zool. Exper., Iv. (1916) pp. 417-82 (2 pis. and 6 figs.). 

 t Arch. Zool. Exper., Ivi. (1916) pp. 25-157 (3 pis. and 88 figs.). 



