187 



were not very good, the embryos developing only to the beginning forma- 

 tion of the Bipinnaria; the somewhat unexpected fact that this species 

 has a typical pelagic larva was, however, already proved by this first 

 attempt. On the 18th of June I had the pleasure of seeing a female spec- 

 imen, kept in a dish together with a number of other specimens, discharge 

 its eggs, from which an excellent culture was obtained. I regret not having 

 noticed the exact size of the eggs, only stating that they are small; I think 

 I remember that they were of yellowish colour. The cleavage began very 

 soon after the fertilization; the fact that I have made no notices about 

 the cleavage process most likely indicates that it is of the usual, regular 

 type. After 16 hours the gastrula stage was reached, and at the age of 

 two days the embryos had the typical Bipinnaria-shape. The larvae were 

 generally found swimming close to the bottom of the dish. At the age of 

 10 days the enterocoel pouches had united in the anterior end of the body. 

 At the age of 18 days some few of the larva? were in the metamorphosis- 

 stage and, accordingly, had reached the full larval shape. 



The young larva (PI. XXXIII, Fig. 1) looks very much like the Aslro- 

 pec/en-larva, with small, non-contractile processes; there are no postoral 

 or preoral processes. The suboral cavity is small, not very deep. It is espec- 

 ially noticeable that the vibralile band of the ventral median process is 

 as distinctly developed as the rest of the bands, contrary to what is gener- 

 ally the case in larva? having a Brachiolaria-stage. It was, therefore, a 

 great surprise to me to see that this larva in its final stage really is a 

 Brachiolaria (PI. XXXIII, Fig. 2), though of another type than the Bra- 

 chiolaria of Asterias. At each side of the fairly large sucking disk there 

 is a small brachiolarian process with a few papilla? at the end. I was un- 

 able to ascertain the exact number of these papillae, as also to ascertain 

 whether the vibratile band continues along the paired brachiolarian pro- 

 cesses. The median process is only slightly transformed, retaining its flal 

 shape, and its vibratile band bordering it as in the younger stage; only 

 a row of small papillae, 3 5 in number, along each side, inside the band, 

 indicates its brachiolarian character. The other processes remain unaltered, 

 short and small. The length of the fully formed larva is ca. 0,6 7 mm. 

 It is unpigmented, 



Asterina (Patiriella) regularis Yen-ill. 



Among a large number of specimens of this species which I collected 

 on the rocky shore at the Island Bay, outside Wellington, Xew Zealand, 

 on the 17th of February 1915 I found a few specimens to contain partly 

 ripe sexual products. The artificial fertilization which I undertook was not 



24* 



