578 SUMMARY OF CURRENT RESEARCHES RELATING TO 



directed to the barrel-like shape, the small fins, the minute eyes, the 

 absence of tentacles, and the complete covering of the chambers of the 

 shell by the mantle, which is very thin at this region. 



7- G-astropoda. 



Calcigerous Cells in Snail's Liver.*— S. Griinbaum describes 

 these well-known cells, triangular in form, with a broad base, with a 

 polymorphic nucleus, with bodies analogous to parasomes, with mito- 

 chondrial apparatus and fats in the cytoplasm, with yellow excretory 

 corpuscles, and with very abundant calcareous corpuscles. 



Structure of Helcioniscus ardosiseus.t — M. E. Schuster gives a 

 detailed account of this limpet. We may refer to some of his more im- 

 portant results. The epithelium of the body is without cilia. The chief 

 inte2:umentary glands are the diffuse mucus-making sole-gland and 

 others which produce a repulsive secretion. The shell is formed from 

 the upper surface of the mantle margin, and consists of periostracum, 

 ostracum (mostly two-layered) and hypostracum (also two-layered). 

 Muscle fibres pass from the body directly on the shell ; each fibre is a 

 single cell with a central or excentric nuclei ; no cross-striping was seen. 

 The radula shows a rudimentary rachis tooth, two lateral teeth, and 

 a marginal tooth. Four pairs of cartilage support the buccal mass, 

 and there is another large cartilage on each side of the head. There 

 is a pair of salivary glands on the gullet and another on the crop. 

 A sub-oesophageal pouch opens into the buccal cavity. The supra- 

 intestinal ganglion is close to the right pleural ; the sub-intestinal is 

 \'ery rudimentary. The lateral sensory line of the foot is not slj-ongly 

 developed. There are two atrio-ventricular valves. The row of 

 branchiae is continued anteriorly over the head. There is both a right 

 and a left reno-pericardial duct, with an epithelial lining like the epith- 

 elium of the pericardium. 



Structure of Oliva peruviana. J — Arthur Kiittler describes this type 

 in detail. There is much ciliated epithelium on the surface of the body. 

 At the anterior end of the propodium there is a gland with two kinds of 

 cells. The uppermost ostracal layer has the pigment. Tliere is no 

 striped muscle. The mid-gut is surrounded by " peri-intestinal con- 

 nective tissue." There are many glands in the outer wall of the pro- 

 boscis and its sheath. The liver shows hepatic cells and so-called 

 ferment-cells. The female reproductive organs are somewhat divergent. 

 All the ganglia except the viscerals and the two intestiuals have coalesced 

 in the nerve-ring. The retina consists of pigment-cells and visual cells. 

 Each statocyst has one statolith and the internal epithelium consists of 

 supporting cells and sensory cells. There is a nephridial gland, but no 

 pericardial gland. 



Structure of Calyptrseids.§ — Hans Kleinsteuber has studied Trochita^ 

 Galyptrsea, and Janacus, and we note some of his results. There is no 



* C.R. Soc. Biol. Paris, Ixxv. (1913) pp. 208-10. 



t Zool. Jahrb., 1913, Suppl. 13, pp. 281-384 (1 pi. and 87 figs.). 



X Zool. Jahrb., 1913, Suppl. 13, pp. 477-544 (51 figs.). 



§ Zool. Jahrb., 1913, Suppl, 13, pp. 38f.-476 (2 pis. and 46 figs.). 



