478 SUMMARY OF CURRENT RESEARCHES RELATING TO 



7' Gastropoda. 



Structure of Crucibulum ferrugineum.* — Karl Scheidig gives an 

 account of the structure of this Calyptrseid. The shell is noteworthy 

 for the curious internal cup-like process which lodges a modified por- 

 tion of the foot. Lateral lobes on the sides of the neck, innervated 

 by the pedal ganglia, represent epipodia. The salivary glands are 

 relatively smaller than in Crepidula. The longitudinal folds in the 

 oesophagus are ciliated and non- glandular. In the " stomach " there is 

 a chitinous cuticle, and the function is that of a gizzard. There is only 

 one hepatic aperture. The hepatic tubuli consist of two kinds of cells, 

 hepatic-cells and ferment-cells. The gill is very strongly developed : it 

 forms almost a circle ; the number of branchial folia is about 900. The 

 auricle of the heart is very large and half -moon shaped ; the ventricle is 

 small. There is no pericardial gland. The hypobranchial gland is 

 divisible, as in most Prosobranchs, into a viscous and a mucous portion. 

 The reproductive system is very simple. There appears to be protan- 

 drous hermaphroditism. As to the nervous system, it may be noted 

 that the cerebral and pedal commissures are clearly seen ; that the right 

 cerebro-pedal connective is constant, while that on the left fluctuates ; 

 that the nerve of the penis arises from the right pedal ganglion ; that 

 there is only one very small visceral ganglion. The osphradium has a 

 somewhat peculiar structure. The eye is essentially like that of the 

 higher Prosobranchs. 



Structure of Choneplax latus.f — Otto Seel describes this member 

 of the Cryptoplacidag, which lives jn the holes in the coral reefs in the 

 West Indies. It has not gone so far as a type like Gryptoplax {Ghito- 

 nellus) fasciatus in the direction of a worm-Uke body, but it shows the 

 same tendency. Its internal structure corroborates the view that it is 

 near the beginning of divergence from an Acanthochitonid Hue. In its 

 oral disk, lateral fold, nervous system, and gills, it shows little divergence 

 from the primitive Ischnochiton type. In its strongly developed mantle, 

 narrowed row of shells, much elongated gut, and in the disposition of 

 the kidneys, it shows approximation to the specialized OhitoneUus type. 



5. Lamellibranchiata. 



Structure of Chama pellucida.J — Emil Grieser has made a study 

 of this Lamellibranch from the Pacific coasts. He describes the complex 

 ridges and grooves of the labial palps, the division of the intestine by a 

 dorsal and a ventral fold into a left and a right half — the intestine 

 proper and the crystalline style caecum, the glandular differentiations 

 associated with the pericardium and the heart, and the peculiarities of 

 the vascular system and nephridia. 



Of especial importance is the differentiation of the buccal nervous 

 system. On each side of the cerebro-pleural ganglion and joined to it 



* Zool. Jahrb., 1913, Supplement xiii. pp. 137-74 (4 pis. and 3 figs.), 

 t Zool. Jahrb., 1913, Supplement xiii. pp. 175-206 (2 pis. and 3 figs.). 

 X Zool. Jahrb., 1913, Supplement xiii. pp. 207-80 (1 pi. and 11 figs.). 



