48 Mr. Broderip and Mr. G. B. Sowerby oti Molltisca. 



the centre, and bearing a striking general resemblance to the external 

 plates of a Land-tortoise's shell. The orifices are very small, and are 

 surrounded by six triangular valvules, each transversely striated, and 

 when shut, rising from the surrounding surface in the form of a cone. 

 The lower or cup-like part is formed of a coriaceous substance, with 

 slight traces of separation into plates, but without internal muscular 

 fibre. In one specimen only there were two irregular somewhat horny 

 plates at the external base of the cup, but not so strongly marked as the 

 upper plates. These lower plates were not to be observed in another 

 specimen which was removed for the purpose of examination from the 

 stone to which it was fixed. 



The learned and accurate anatomical observations on the natural 

 group of Tunicata, by William Sharpe MacLeay, Esq., (Linn. Trans. 

 Vol. XIV. p. 527.) have done so much in elucidation of the hitherto 

 obscure structure of many of these animals, that the specific name above 

 recorded is but a small tribute to the author of such a valuable 



Dentalium filosum. 



jD. testd gracili, tenui, alha,filis octo longitudinalihia, striist transrersix 

 creberrimis ; long. 2-^% poll. lat. y^ po^^- 

 Hah. ad littora maris ad Tennasserira. 



Distinguished from D. octogonum., by its much more slender shape, 

 and its thinner shell ; instead of the eight angles of that species, it has 

 eight distinct, raised, longitudinal threads. Three specimens of this fine 

 species were lately brought to England by Mr. Hay, who himself picked 

 them up on the coast of Tennasserim. 



Cytherea planulata. 



C. testd trigond, depressiusculd, suhcequilateruU ; angulis inferioribux 

 rotundatis ; pallide Jlavicante, radiis numerosis fuscescentibvs ; 

 intus albidd, fusco-violaceo varid ; dente postico remoto ; long. \-°-^ 

 poll. lat. y\ poll- alt. \-{\j poll. 

 Hab. in littoribus Oceani Pacific!, prope Mazatlan. 



A pretty species of Cytherea, which has so much of the general ap- 



