Zoological Society. 4-5i5 



to the end of the nasal bones, in one direction, and to the occiput in the 

 other, — as not being in all cases available : the second distinction, — 

 the flattening of the interorbital space in the Lion and its convexity 

 in the Tiger, — he regarded as being more constant and appreciable 

 than the one just mentioned. There is, however, a distinction 

 which he believes has never been published, which is well marked, 

 and which appears to be constant; for it is found to prevail through- 

 out the whole of the skulls of these animals which he has had op- 

 portunities of examining, including ten of the Lion, and upwards of 

 twenty of the Tiger. It consists in the prolongation backwards, in 

 the cranium of the Lion, of the nasal processes of the maxillary 

 bones to the same transverse line which is attained by the coronal 

 or superior ends of the nasal bones : in the Tiger the nasal pro- 

 cesses of the maxillary bones never extend nearer to the transverse 

 plane attained by the nasal bones than 4-rd of an inch, and some- 

 times fall short of it by irds, terminating also broadly in a straight 

 or angular outline, just as though the rounded and somewhat pointed 

 ends which these processes have in the Lion had been cut oft'. 

 Minor differences, Mr. Owen, remarked, exist in the form of the 

 nasal aperture, which in the Tiger is disposed to narrow down- 

 wards, and become somewhat triangular, while in the Lion its 

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

 longitudinal depression, of the coronal extremities of the nasal 

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

 pression above in most of the Tigers' crania by a small but distinct 

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

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

 infraorbitaiyor«nj/«a in the Lion. These foramina, it is curious to 

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

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

 all the others the foramen was single on each side. 



Specimens were exhibited of Placunanomia: from the collection 

 of Mr. Cuming, and some Notes by Mr. Broderip respecting them 

 were read, from which the following are extracts : — 



Genus Placunanomia. Since my publication of this genus in the 

 4 Proceedings of the Committee of Science and Correspondence*,' 

 Mr. Cuming has found among his stores the following three species 

 in addition to Plac. Cumingii, which I have already recorded : viz. 

 Plac. rudis, foliata, (The outer surface of the lower valve, which 

 has been attached throughout its whole extent, bears a somewhat 

 crystalline appearance; and this observation may be applied to the 

 adhering surface of Plac. rudis,) and echinata. The last-named 

 species varies much in shape, according to circumstances. Mr. 

 G. B. Sowerby possesses one of an irregular ovate form. In- 

 deed Placunanomia, in common with other adherent genera, varies 

 much in .shape, accommodating its external form to the surface to 

 which its lower valve is attached. It is remarkable also for putting 

 on the appearance of other genera or species; and this, with the ex- 

 treme closeness of the adhesion of the lower valve, has been per- 

 haps one of the causes why it has escaped the notice of zoologists. 



• See Lond. and Kdinb. Phil. Mag., vol. i. p. 894, 



