Miscella n eo us. 151 



Several well-known teachers and lecturers have expressed their 

 warm approval of the scheme. 



Communications may be addressed to Dr. Andrew Wilson, 110 

 Gilraore Place, Edinburgh, or to Mr. William Lant Carpenter, 

 36 Craven Park, Harlesden, N.W. 



On a Starfish from the great Depths of the Atlantic, furnished with 



a Dorsal Peduncle. By M. E. Perrter. 



Among the Stellerida collected during the expedition of the 

 i Travailleur ' in 1SS0 there are two individuals of a species of 

 Starfish* which present the perfectly exceptional character of being 

 furnished with a dorsal peduncle, exactly comparable, as to its 

 position, to that which supports and fixes to the ground the young 

 Comatuke and the adult Crinoids of all the other families. While 

 the Crinoids, which are evidently the most ancient of the Echino- 

 dermata, are all attached, at least during their youth, the Echino- 

 dermata which form the other classes of that subkingdom are free 

 during their whole lives ; and it would be particularly interesting to 

 find in that class, which we have every reason to consider the most 

 ancient after that of the Crinoids, traces of a mode of existence 

 which was general among the latter animals, namely fixation to the 

 ground. Some characters of the Starfishes which we have now to 

 speak of seem to indicate that the dorsal appendage with which 

 they are furnished is really the homologue of the peduncle of the 

 Crinoids. 



Our two Starfishes, which we propose to name Caidaster peduneu- 

 latus, are of different ages. The larger one has a radius of only 

 5 millim. to the extremitv of the arms, and of 3 millim. to the 

 summit of the interbrachial arch. In both the summit of this arch 

 is occupied by a sort of fissure furnished with papillae, separating 

 the marginal plates which belong to one arm from those belonging 

 to the other. The fissures are prolonged upon the disk, on the 

 dorsal surface, each by a double series of spines. These rows of 

 spines converge towards the base of the dorsal appendage. The 

 marginal plates, which are not very visible, only form a single row, 

 as in Ctenodiscus ; there are five of them to each arm ; the madre- 

 poric plate, which is tubercular, is enclosed in one of the inter- 

 brachial fissures. The arms are short, strongly recurved over the 

 disk, and each terminated by three long spines ; the ambulacral 

 tubes, destitute of suckers, are arranged in two series ; there are 

 not more than eleven pairs. The dentary plates have the form of 

 simple scales, uniting at their free extremity to be produced into a 

 sort of unpaired conical tooth. The dorsal integument is soft ; we 

 cannot distinguish plates of any kind upon its surface. The dorsal 

 appendage, 2 millim. long, and consequently nearly as long as the 



These two starfishes were obtained off the north coast of Spain, 

 one at 1900, the other at 2(W0 metres. 



