196 



UmkI themselves very easily to aililicial I'eilili/alioii nor lo breediii" in 

 aquaria. 1 was nol prepared to use that method (lurint> my voyage, partly 

 because my former experiments with llulolliurui nigra did nol make clear 

 to me the difficulties generally met with in the study of the development 

 of Hololhurians by means of artificial fertilization, partly because it would 

 have been rather troublesome to carry along such a live-box on the long 

 voyage. 



As is the case with the Asteroid-larvae, the larva^ of the Ilolothurians 

 are as a rule not found very well preserved in plankton samples, and the 

 material which I have gathered in that way is not very important, present- 

 ing no new larval types. The contribution to the knowledge of the llolo- 

 thurioid-larv8e which I can give here, is accordingly rather small, especially 

 as compared with that of the Mchinoid- and Ophiuroid-larvai. 



Stichopus californicus (Stimpson). 



PI. XXXIII, Figs. 8—9. 



This species, which occurs fairly commonly along the rocky shores near 

 the Biological Station at Nanaimo, was found to have ripe sexual products 

 in June. Fertilization was undertaken repeatedly and with good success, 

 though the percentage of the fertiUzed eggs was ahvays rather small. I 

 have no notices about the first developmental processes, except that the 

 embryos were found in the blastula stage one day, in the gastrula stage 

 two days after fertilization; the formation of the Auricularia may begin 

 on the second day. At the age of about (> days the larva; were typical 

 Auriculariie, provided with a starshaped calcareous body in the left postero- 

 lateral process. In this stage the larvae remained till the age of ca. 3 weeks, 

 no further development taking place. 



The shape of the larva (PI. XXXIII, Figs. 8—9) 

 is somewhat elongated. The preoral band is highly 

 arched; there are no preoral processes, but the frontal 

 area is distinctly constricted at the level of the ujjper 

 end of the oral cavity, the anterior part forming a 

 i-ig. 101. Spicules from joundcd lobe; the corresponding part on the dorsal 



larva of Stichopus rati- ' ' 



fornicus. *"h. The small side is mucli uarrow'er. The dorsal and posterolateral 

 spicule to the right from lobcs are fairly distinct. The postoral band is strongly 



the right posterolateral • lu -in i i i ■• ii i 



' _^ convex in the middle so as almost lo suit tiie shape 



process. ' 



of the preoral band. The anal area is markedly con- 

 stricted at the lower end of the body, the posterior edge of which is 

 distinctly concave. The calcareous body (Fig. 101) has the shape of an 

 irregular star; very rarely there is a small, irregular calcareous body also 



