Ophiurae 553 



When the daily temperature average is about 20 C, the larvae reach 

 their full development in 2 1 days. Keep the culture jars at temperatures 

 somewhat below 20 for best results ( i7°-20° C). Higher temperatures 

 increase the growth rate of bacteria markedly. 



Direct sunlight and strong daylight are injurious to the larvae. The 

 number of animals decreases rapidly in a culture exposed to bright 

 light as compared to a shielded one. It is sufficient to keep the culture 

 vessels in a dark corner of the laboratory or to place them in uncovered 

 wooden boxes painted a dull color on the inside. 



Bibliography 



Agassiz, L. 1877. North American starfishes. Mem. Mus. Comp. Zool. Vol. 5. 

 Delage, I. 1904. filevage des larves parthenogenetiques d' Asterias glacialis. Arch. 



de Zool. Experimentale, 4 Series, Vol. 2. 

 Gemmill, J. F. 1912-1915. The development of the starfish Solaster endeca. 



Trans. Zool. Soc. London, Vol. 20. 

 1914- The development and certain points in the adult structure of the 



starfish Asterias rubens. Philos. Trans. Royal Soc. London, Series B, Vol. 205. 



Reference 

 Order spinulosa 



For the culture of Solaster endeca see p. 550. 



Class Ophiuroidea, Order ophiurae 



OPHIODERMA BREVISPINA 



Caswell Grave, Washington University 



TO OBTAIN the eggs of Ophiodcrma brevispina, collect twenty-five 

 or more adult animals from the grass roots or sedimentary debris on 

 the shallow flats of their habitat (Beaufort, N. C, or Woods Hole, 

 Mass.) during the breeding season (June and July) on the day when 

 developing eggs are desired and place them in a large aquarium jar until 

 sunset. To keep the animals in good physiological condition, the jar 

 should be placed in running seawater or suspended beneath a wharf. 

 About sunset the animals should be transferred to another aquarium 

 jar of fresh seawater and placed on a table before a window. For a time 

 after the transfer of the animals they may be observed to huddle to- 

 gether near the least illuminated side of the jar but as dusk comes on 

 they become active, crawl about over the bottom and attempt to climb 

 the side of the jar. 



At about 8 o'clock spawning may be expected to begin. It is initiated 

 by the males but very soon after sperm has been emitted the females 

 begin to liberate eggs. The presence of sperm in the water, or some 

 substance associated with sperm, seems to be a necessary stimulant to 



