191 

 Gymnasteria carinifera (Lamk.). 



PI. XXXIII, Fig. 6. 



This species was found, though not very commonly, in the rock-ponds 

 near Hilo on Hawaii, and proved to have ripe genital products during the 

 time of my stay there. Fertilization was undertaken on the 7th of April 

 and proved successful. The next day the embryos were in the blastula- 

 stage; the ectoderm is folded as in Astropeden, Luidia etc. At the age of 

 two days they were in the gastrula-stage, being somewhat elongate in 

 shape; on the third day the formation of the mouth and the enterocoel- 

 pouches was beginning, and on the fifth day the embryos had the shape 

 of young Bipinnariae, showing, when disturbed, the usual contraction of 

 the dorsal side, so characteristic of young Bipinnariae. At the age of three 

 weeks the larvae were well developed Bipinnariae of the rather characteri- 

 stic shape shown in PI. XXXIII, Fig. 6. The most conspicuous feature is 

 the great width of the dorsal side in the anterior part, which very con- 

 siderably surpasses that of the frontal area. The preoral band is much 

 raised in the middle, forming almost an acute angle; the frontal area is 

 much narrowed at the base of the median process, but there are no preoral 

 processes. Both the ventral and dorsal median processes are broadly 

 rounded and rather . unusually short, though not quite as short as they 

 appear in the figure; the specimen figured is somewhat contracted on the 

 dorsal side, these processes thus being somewhat dorsally directed so as 

 to appear shorter than they are in reahty. The posterolateral processes are 

 very short, merely indicated, the posterior end of the body being rather 

 narrow. There are no postoral processes; the postoral transverse band is 

 straight. — The larva is unpigmented ; I have noticed in the living larvae 

 the existence of fine, isolated muscle fibres. The body length of the larva 

 is ca. 0,4 mm. 



Beyond the stage described the larvae did not develop. The culture was 

 kept for a Uttle while yet (the specimen figured is 26 days old), but no 

 fur4;her development was observed. The important question must then be 

 left undecided, whether this larva has a Brachiolaria-stage. This is to be 

 expected, since another form of the same family, Porania pulvillus, has 

 a Brachiolaria-stage; but the proof is wanting. 



Ophidiaster Guildingii Gray. 



During my sojourn at Tobago, B. W. I., with the Carnegie Expedition 



in April 1916 I found some few ripe specimens of this species on April 



19th, which were used for fertilization. The eggs are very small, only 0.11— 



0.12 mm. The cleavage is quite regular; the gastrula is formed, before the 



