2 AET. 1. T. FUJITA : ON THE FORMATION 



almost the same as those obtained from Siphoncma, there being 

 only slight differences in minor details. 



The present paper embodies the more essential points brought 

 out in the investigation on these two animals. 



THE EGGS. 



The eggs of both species here to be considered are deposited 

 on rocks between the tide-marks from the early pai't of March 

 till late in June. Each form presents so many characteristic 

 differences in egg masses, that it is convenient to describe them 

 under separate headings. 



Eggs of Sipho7iaria : — The eggs of Siphonaina are almost 

 always found in masses, the shape of which may be described as 

 an elliptical loop (Fig. 1, Plate I), the last laid portion usually 

 resting on the portion laid first. When oviposition is completed, 

 the head of the animal is j^ointed in the direction of the arrow 

 in Fig. 1. PI. I. When magnified the mass is seen to be formed 

 of an innumerable number of oblong vesicles, which are linked 

 one to another by a fine thread, the whole being cemented 

 together by a gelatinous coating. Each vesicle is enveloped in 

 two membranes, very thin and transparent, which are closely 

 applied to each other, and separated only at the poles of the 

 longer axis (Fig. 4). The egg (Figs. 2 and 4 e) found in each of 

 these vesicles which must be regarded as the chorion lies rather 

 eccentrically in the portion furthest removed from the genital 

 opening. It is perfectly spherical in form, and is 0.1 mm. in 

 diameter. When freshly deposited it is very slightly tinged with 

 yellow, but in course of development it gradually becomes white. 

 In far advanced stages especially in the larval form its color 



