352 SUMMARY OF CURRENT RESEARCHES RELATING TO 



zizyphinus and Gibbula cineraria, two common Trochidas. The parasite 

 is elongated, vermiform, and almost cylindrical ; it almost fills up the 

 rectum, and only one occurs in each host. The colour is bright red, and 

 can be seen through the skin of the Trochid. Many specimens were 8 mm. 

 in length, including the ovigerous sacs, and some were longer. The 

 head-region is well-marked and bears antennules, hooked antennas, re- 

 duced mandibles, and vestigial maxillas. The thorax bears four pairs of 

 biramose pereiopods with hooked exopodites, and a vestigial fifth pair. 

 The first abdominal segment bears the genital apertures and the ovigerous 

 sacs. There is a resemblance of convergence between this new form and 

 Mytilicola intestinalis Steuer from the mussel. 



Germinal Layers in Cyclops viridis.* — Karl Fuchs has studied 

 the cleavage and gastrulation in this Copepod. His results confirm the 

 conclusion that the endoderm in Entomostraca arises from a single 

 quadrant or octant, and that the mesoderm arises from the portions of 

 the vegetative quadrants or octants which adjoin the pole. The meso- 

 derm forms an arch around the primitive endoderm-cell (and an apposed 

 primitive germ-cell or " Urmesodermzelle "). This arch afterwards 

 closes to form a ring. The numerical strength of the mesoderm ring 

 varies with the disposition and division- direction of the polar octant 

 portion. 



In a number of types (Moina, Polyphemus, Cyclops), a primitive 

 germ-cell arises in a polar position along with the primitive endoderm- 

 cell. In some other types {Cetochilus, Lepas) a primitive mesoderm-cell 

 is constricted off on the equatorial side from the primitive endoderm- 

 cell. 



Annulata. 



Japanese Aquatic Oligochseta.t — Ekitaro Nomura describes Limno- 

 drilus gotoi Hatai and L. ivilleyi sp. n., which he compares very 

 carefully. The former species also occurs in Ceylon. Details are given 

 of the minute structure of the body-wall ; the sette and the setigerous 

 sacs ; the alimentary canal : the septa and septal sacs ; the amcebocytes ; 

 the nephridia ; the central nervous system ; and so on. 



New Myzostomid.J — D. Fedotov describes Protomyzostomum poly- 

 nepitris Fedotov, a new genus which he found in the gonads of 

 Gorgonocephalus eucnemis in the Kola Fjord. It is a flat, Planarian- 

 like worm up to 3 cm. in length, orange-coloured or somet/imes reddish. 

 The margin is without cirri and somewhat thickened. There are five 

 pairs of weakly developed almost rudimentary parapodia, and corres- 

 ponding to these, on the back or on the margin, there are five pairs of 

 lateral organs. There is a thin cuticle, the body-epithelium is sunk in 

 below the sub-cuticular musculature, and there are no cilia ; the position 

 of both mouth and anus is terminal. There is no proboscis. The 

 muscular pharynx is short ; the intestine has 8 to 13 pairs of lateral 

 main branches ; the rectum is very short, and the cloaca is rather long. 



* Zool. Jahrb. Abth. Anat., xxxviii. (1914) pp. 103-56 (3 pis. and 6 figs.). 



f Journ. Coll. Sci Tokyo, xxxv. (1913) pp. 1-49 (34 figs.). 



X Zeitschr. wiss. Zool., cix. (1914) pp. 631-96 (4 pis. and 2 figs.). 



