288 BR. ARTHUR WILLEY ON 



I observed the fixation of the larva to a fragment of red sea- 

 weed by means of the adhesive processes, and kept it overnight, 

 alive and attached. The bipinnarian arms became miich wrinkled 

 and constricted ; the adhesive processes were stretched wide apart 

 so as to allow the median suctorial pad to touch the seaweed 

 between them. The quinque-radiate disc swayed vertically and 

 freely in the water. The accompanying semidiagrammatic sketch 

 (text-fig. 54) will give a better idea of the attached larva than will 

 a verbal description. 



A figure from another aspect, after Johannes Miiller, of a 

 Brachiolaria fixing itself in a difi'erent attitude, is reproduced in 

 the Cambridge Natural History (Yol. i. 1909, Echinodermata, 

 by E. W. MacBride, see p. 613). 



I was at first puzzled by the statement in Delage et Herouard 

 (Traite de Zoologie Concrete, T. iii. Les Echinodermes. Paris, 

 1903, see pp. 80-81) that the median epithelial pad, between the 

 bases of the brachiolarian arms, is a ciliated sucker (ventouse 

 ciliee,) as I had observed no sign of ciliary action upon it. In a 

 subsequent investigation Delage himself found no indication of 

 ciliation of the median suctorial pad (Yves Delage, " Elevage des 

 larves parthenogenetiques d'Asterias glacialis" Ai-ch. zool. exper. 

 ser. 4, ii. 1904, seep. 38). 



In larvaj of Asterias glacialis raised by Delage from unfertilised 

 eggs treated with carbonic acid, the paired adhesive arms 

 appeared first, towards the middle of the third month of the 

 culture. Brachiolaria which had reached the fourth month 

 in Delage's experiments, showed clearly the initial phenomena 

 of the metamorphosis ; they ceased to swim, the bipinnarian 

 arms became shrivelled, and the larvje adhered by the mobile 

 brachiolarian arms, occasionally shifting their position. 



Amongst the numerous larvae seen by me at St. Andrews, 

 many of which were sketched from life, I only observed the 

 fixation to occur on the part of the oldest, when the asterodisc 

 was most opaque. 



The larva does not remain fixed irrevocably at the first spot 

 where it alights upon the bottom ; but it never swims again. 

 Tlierefore it cannot be said that the adhesive arms serve merely 

 for occasional attachment. They represent a definite stereotropic 

 mechanism. 



Bolina. — On August 14th at low tide,about 7 A.M.,Dr. Huntsman 

 found quantities of Bolina alata at the foot of the wharf, adrift 

 in shallow water. I embraced the opportunity thus afibrded of 

 making a fugitive study of this remai'kable and fragile Ctenophore 

 which defies all methods of preservation. 



L. Agassiz (" Contributions to the Natural History of the 

 Acalephse of North America." Mem. Amer. Acad., Boston, 1849) 

 described the various attitudes of Bolina, including one in which 

 the characteristic mantle-lobes are spread out lengthwise, at 

 right angles to the secondary axis in which the tentacles lie, and 



