18G2.] MR. LOVELL REEVE ON A NEW I'HYSA.. 105 



corresponding to the greater relative depth of the calcarine sulcus, 

 exists in this brain, as in that of Lemur and Galago and all the true 

 Apes. 



" The brain of Stenops conforms closely with that of Lemm\ both 

 in its general form and the disposition of its surface-markings. The 

 principal differences that were observed between them are described 

 in the paper ; and then follows a comparison of the brains of these 

 two animals with those of the higher Quadrumana. As has been so 

 well shown by M. Gratiolet, in his beautifully illustrated memoir 

 upon this subject, a certain type both of general configuration and 

 of surface-markings pervades the brain of all the Primates, from 

 Man to the Marmoset. From this type M. Gratiolet excludes the 

 Strepsirrhine Quadrumana, placing them, with the Insectivora, in a 

 group of Mammalia whose cerebral organization he considers to be 

 quite distinct from that of the two first families of Quadrumana. 

 The author of the present paper finds reason to dissent from this 

 proposition, and upon cerebral characters alone would retain the 

 Lemurs in the position assigned to them by the majority of systematic 

 zoologists — admitting, however, that, while possessing certain very 

 important points of structure peculiar to the Primates, they are in 

 man}"^ respects, especially in the shortness of the posterior lobes, an 

 aberrant group, forming a transition towards the Cheiroptera, Car- 

 nivora, and other inferior Mammalia." 



This paper will be published at full length in the Society's 

 'Transactions,' and appropriately illustrated. 



The following paper was read : — 



On a new form of Physa, of the section Ameria, re- 

 ceived FROM George French Angas, Esa., of xIngaston, 

 South Australia, Corresponding Member of the So- 

 ciety. By Lovell Reeve, F.L.S. 



The genus Physa occurs abundantly in the ponds and ditches of 

 Europe and North America, and throughout the intertropical main- 

 land and islands of the Eastern hemisphere. But in all the nume- 

 rous species belonging to this wide range of geographical distribution 

 the shell is regularly convex and smooth. In Australia and New 

 Zealand a new type appears, in which the shoulder of the whorl is 

 broadly angled. Eight species, in the collection of Mr. Cuming, 

 characterized by this angular growth, some of them with the spire 

 flatly immersed — two from New Zealand, the rest from North 

 Austraha, Port Essington, and the Boyne, Calliope, and Fitzroy 

 Rivers — have been lately described by Mr. Henry Adams under the 

 new generic title of Ameria, all being uniformly smooth. They differ 

 from the rest of the Physa in being formed on the angular type ; 

 they resemble them in being still destitute of sculpture. The form 

 of Physa now introduced from South Australia is of the angular 

 type, but it differs from all others in being sculptured transversely 

 with thread-like ridges. The shells of the allied genus Limncea are 



