Report on the Invertebrata of Massachusetts, we find 

 nothing further. In that Report, Muller's squamota and 

 peniactes are mentioned but not described. Le Sueur's 

 Briareus is noticed with a doubt, and a new species, Chiro- 

 dota arenata, is defined. Another had been previously 

 named in the Boston Journal of Natural History, by 

 Couthouy, as Hoi. chrysacanthophora ; but this species, 

 which is quite abundant in Massachusetts Bay, does not 

 belong to the Holothuridce. 



After some general statements in relation to the ana- 

 tomical structure common to all members of the family, 

 Mr. Ayres proceeded to describe a species found by him at 

 Sag Harbor, and apparently identical with Le Sueur's 

 Brinreus. It differs, however, so remarkably from all pre- 

 viously recognized types, that a new genus is necessary for 

 its reception. For this the name SderodactyJa is proposed, 

 and the species will be designated Scl. Briareus, The 

 genus is characterized as follows: — 



Gen. ScLERODACTYLA Ayrcs. 



Extremities somewhat elevated, thus distinguishing a superior 

 and inferior side. Suckers very numerous, scattered over all 

 parts of the body, but most thickly beneath. Tentacula, ten ; 

 of which two or three are smaller than the others, each sup- 

 ported on a stem consisting of a solid, ramified, calcareous tube, 

 which is continued into the branches, but not to the extreme 

 divisions. Of course the tentacula are not capable of much 

 change in length. The solid tube has suggested the generic 

 name. Oral circle not composed of separate pieces, but of a 

 single, broad, thin, calcareous plate, with points projecting ante- 

 riorly and posteriorly. Stomach very strongly muscular, intes- 

 tinal tube of uncommon length. Respiratory trees largely 

 developed, much branched. 



The genus appears allied to Sporadipus and Anaperus. It 

 may be here remarked that the partial development of some of 

 the tentacula is not at all uncommon ; it occurs in Thyonidium, 



