652 SUMMARY OF CURRENT RESEARCHES RELATING TO 



depths below 10 in. Eggs are brought forth only in the cold season. 

 These observations were made on the Dratzig and Madii lakes in N. 

 Germany. 



Cave-dwelling G-alatheid from the Canary Islands.* — W. T. 

 Caiman discusses Munidopsis polymorpha Koelbel, collected by Mr. 

 Fairfax Prevost in a cave on the island of Lanzarote. The occurrence 

 in a littoral cave is very interesting, in view of the exclusively deep-sea 

 habitat of the other (102) species of the genus. It seems probable that 

 the present inhabitants of the cave are the descendants of some deep- 

 water species which, having been carried into the fissures by which the 

 cave communicates with the sea, found there an environment suitable, at 

 least in the absence of light, to its habits. 



Polyspermy and the Culture of Spermatozoids.f — A. Labbe finds 

 that the ovary of Carcinus a few hours after fertilisation is full of 

 spermatozoids in different stages of development. The eggs are full, 

 and in the yolk are all stages between spermatozoids and merocytic nuclei. 

 Many are digested in the ovarian cytoplasm, many merocytic nuclei 

 undergo karyolytic degeneration, and only a small number persist in the 

 vitellus till they reach the stage of definite nuclei. Full development 

 can be secured by artificial cultures of spermatozoids upon lecithin. 



Annulata. 



Structure and Habits of Poecilochsetus.* — E. J. Allen gives a very 

 complete account of the habits and structure of a new species, P. serpens, 

 of this genus. The larva has been known for years at Plymouth, but 

 only recently has the adult been discovered. It constructs U-shaped 

 burrows in the sand which is exposed at low spring tides, and its area 

 of distribution is very restricted. When at rest the animal lies in its 

 tube with the two long palps extended in front. A constant current of 

 water, drawing small particles with it, is kept up through the tube by 

 means of an undulatory movement of the body, and of a fan-like move- 

 ment of the parapodia and bristles. If the animal reverses its position 

 in the tube, the direction of the current is immediately reversed. The 

 worm does not possess jaws ; its food appears to consist of fine organic 

 particles and small organisms carried in with the current. Pcecilocluctus 

 appears to breed practically the whole year round. The larva is re- 

 markable for the late stage of development to which it retains the 

 pelagic habit. One of the diagnostic features of the adult is the smooth 

 anterior dorsal surface, with few tubercles. Parapodial cirri of segments 

 7-13 are different from those in the rest of the body, being flask- 

 shaped, with long, stiff necks. The second and third segments have short, 

 stout spines in the neuropodium. The nuchal organ is greatly developed, 

 forming three long tentacle-like processes. 



Branchial Vessels of Sternaspis.§ — E. S. Goodrich points out that 

 the so-called supporting " axis " of the branchial artery is in reality a 



* Ann. Nat. Hist., xiv. (1904) pp. 213-8 (1 fig.). 



t (otnples Eendus, cxxxix. (1904) pp. 75-7. 



% Quart. Journ. Micr. Sci., xlviii. (1904) pp. 79-151 (6 pis.). 



S Tom. cit., pp. 1-10 (2 pis.). 



