THE NAUTILUS. 43 



water issuing from the Rio La Plata acts as an effective barrier 

 against the more southern extension of shallow water species which 

 may reach to its northern point of entrance; so that we may expect 

 that few, if any, of these northern stragglers will be found south of 

 Montevideo. 



In the following list will be found the names of the species received 

 from Dr. von Ihering and a few, not hitherto noted, from the Alba- 

 tross collection, the whole embracing between fifty and sixty species, 

 a good many of which have not hitherto been identified from the 

 region in question, and two of which appear to be new to science. 

 The northern range of most of the species common to the northern 

 Antilles and to the coast of the United States will be found entered 

 against the name of the species in Bulletin 37 above referred to. 

 In some cases the identity of the species has hitherto been obscured 

 by the southern specimens having been separately named ; as in the 

 case of I'agelus plateiisis Orh. which, is positively indistinguishable 

 by any character from T. caribceus. 



The localities are Santa Caterina near San Francisco, in about 

 Lat. 26° S. ; Rio Grande do Sul in S. Lat. 32° 30' ; and the mouth 

 of the Rio La Plata near Montevideo and Tozitos in about S. Lat. 

 35°. 



Ostrea virginica Gmelin var. ])uelchana Orb. Santa Caterina. 

 O. cristata Born. Santa Caterina. 

 Placunanomia rudis Brod. Santa Caterina. 

 Modiola sulcata Lam. Rio Grande do Sul. 

 Mytilus canaliculus Hanley (edulis of E. A. Smith). Rio Grande 



do Sul. 

 Mytilus magellanicus Reeve. IVIontevideo. 

 Area Candida Chemnitz. Santa Caterina. 

 Area martinii Recluz. Santa Caterina. 

 Area imbricata Bruguiere. Santa Caterina. 

 Area americana Gray. Santa Caterina. 

 Area incongrua var brasiliensis Orb. Santa Caterina. 

 Lucina jamaicensis Lam. Santa Caterina. 

 Divaricella quadrisulcata Orb. Santa Caterina. 

 Chama congregata Conrad. Santa Caterina. 

 Cardium brasiliensis Lam. Santa Caterina. 

 Cardium muricatum L. Santa Caterina. 

 Dione circinata Lam. Santa Caterina. 

 Dione purpurata Lam. (+ ligula Anton). Rio Grande do Sul. 



