1844.] Linnean Society. 185 



Gen. Amphidetus, Agansiz. 

 Of this genus Prof. Forbes describes a new species nearly related 

 to Spat, cordatus of Pennant, which he characterizes as follows : — 



A. Mediterraneus, Aorso cor\vex\\.\sc\\\o ; depressione subplano; impi-es- 

 sione scutiformi, extremitate anali truncaia iinpressa cauda prominenti 

 acuminata, ventre piano ; area post-orali lanceolata. — Long, ly^ unc. ; 

 lat. lTV;alt. IJ^. 



Of this species, which was taken in a few feet water in the Island 

 of Paros by Capt. Graves, but which Prof. Forbes has dredged as 

 deep as twenty fathoms, the author gives a detailed description ; and 

 particularly notices the occurrence on each side of the madreporiform 

 plate, obliquely behind the posterior ovarian foramina, of a minute 

 perforation, surrounded by a circle of minute spiniferous tubercles. 

 Similar perforations similarly encircled are seen between each of the 

 ovarian foramina laterally and anteriorly, so that their total number 

 is five. These, the author states, are the eye-sockets with their 

 protecting spines or eye-lids. Their presence, he adds, is unnoticed 

 in any description of the species of Spatangacece, though they are 

 doubtless to be found in all. 



Fam. Clypeasteri^. 

 Gen. EcHiNocYAMus, Leske. Fibularia, Lam. 

 Echinocyamus pusillus is abundant throughout the Egean Sea, 

 being thrown up in shell-sand and equally plentiful at all depths be- 

 tween one and a hundred and ten fathoms. Dead specimens were 

 even dredged at a depth of two hundred. Specimens taken alive in 

 the European seas are undistinguishable from those found in the an- 

 cient tertiaries of the Paris basin, in the miocene strata of Touraine 

 and the Crag, and in the pliocene beds of the Mediterranean. Prof. 

 Forbes regards Fibularia Tarentina, Lam., Fih. Ovulum and probably 

 Fib. angulosa as synonyms of this species. 



Fam. CiDARiD^. 

 Gen. Echinus, L. 



Echinus esculentus, L., was very rarely met with in the Egean Sea ; 

 while, on the other hand, Ech. lividus. Lam., was most abundant, 

 being always littoral and covering the rocks within a fathom of depth, 

 but never, so far as Prof. Forbes has observed, boring into them. 



A living species which the author is unable to distinguish from 

 the fossil Echinus monilis, Defr., was found very abundantly at the 

 depth of between twenty and a hundred fathoms. It would appear 



No. XX. — Proceedings qv the Linnean Society. 



