tendency is towards a square sliape; in the deeper sinking, in a 

 longitudinal depression, of the coronai extreniities of the nasal 

 bones in the Tiger than in the Lion; in the bounding of this de- 

 pression above in most of the. Tigen' crania bj' a small but distinct 

 semilunar ridge, vvliich is not found in those of the Lion; and in the 

 larger comparative size, chiefly in their transverse diameter, of the 

 infraorbitalybra>?u«a in the Lion. Thesejbramina, it is curious to 

 observe, are double either on one or both sides in the only four 

 crania examined of Lions vvhich were known to be Asiatic, while in 

 all the others iheforamen was single on each side. 



Speciraens were exhibited of PlacunanomicB from the collection 

 of Mr. Cuming, and the fol!owing Notės by Mr. Broderip respecting 

 them were read. 



Genus Placunanomia. 



Since my publication of this genus in the ' Proceedings of tlie 

 Committee of Science and Correspondence,' (Part II. p. 28.) Mr. 

 Cuming has found among his stores the following three species in 

 addition to Plac. Cumingii, which I have aheady recorded. 



Placunanomia rudis. Plac. testu sordide alba, crassd, concen- 

 trice irregularitcr cori-ugatu, intiis nitide politd : alt. 1|, long. lį, 

 lat. š poli. 

 Hab. in India Occidentali. 

 Obs. Ostrece edulis speciem referens. 



Mr. Cuming detected this Placunanomia attached to a Spondylus 

 croceus. — W. J. B. 

 /3 y*7 Placunanomia foliata. Plac.testdsubdiaphand,subcirculari, 

 rudi, subfoliatd, sordide alba, intiis splendente ; valvce snperioris 

 medio purpureo-fusco : alt. Ii, long. l\, lat. -,%■ poli. 

 Hab. in sinu Guayaąuil Columbiae Occidentalis. (Isle of Mu- 

 erte.) 



Dredged up attached to a dead Pinna from a bottom of sandy 

 mud, at the depth of eleven fathoms. 



Tiie surface of the inside of the lower valve is uneven but lustrous, 

 and of a hue somewhat approaching to golden. The inside centre 

 of the upper valve is of a rich purple brown. The outer surface of 

 the lovver valve, which has been attached throughout its whole ex- 

 tent, bears a somewhat crystalline appearance ; and this observa- 

 tion niay be applied to the adheiing surface oi Plac. rudis. In the 

 last-mentioned species this portion is comparatively small, and the 

 eye vvill imraediately detect it from the contrast which it affords 

 with the dull exterior of the part which was free. — W. J. B. 

 Placunanomia echinata. Plac. testd subtumidd, valvd supe- 

 riore seriatim echinatd, limbo purpurascente : alt. Ii, long. lį, 

 lat. 3 poli. 

 Hab. ad Insulam Nevis. 



Dredged up attached to shells, by Mr. Powers, from sandy mud 

 at a depth of six fathoms. 



