314 Wotes on certaiyi Species of Cyrena and Cyrenella. 



XXXI. — Notes on the Cyrena sahnacida and the Cyrenella 

 Americana of Morelet. 



Br TKmple Prime. Read June 24, 1861. 



In 1851 Mr. Morelet, in his work on the new species of shells 

 from Cnba and Centi-cal America, Part II., p. 26, gave descrip- 

 tions of the above two species, to which I would beg to call the 

 attention of concholog-ists. 



Tlie C. sahnacida is a representative of that class of Cyren^e 

 which, differing from tlie restof tlie species of this genus which 

 live in fresh water, inhabits brackish waters at the outlet of 

 rivers into the sea. 



Tlie C. niaritima C. B. Adams, and the C. Ciihensis Prime 

 are as yet the only other species of this group known to us; 

 but it is not improbable that when researches shall have been 

 extended this number will be increased. 



The discovery of Cyi-ense in brackish water is a fact of some 

 importance to geologists, which was duly appreciated by the 

 late Mr. D'Orbigny in one of his works. 



The Cyrenella Ainericana^ I will remark, is the first species 

 of the genus which has been found on this continent. 



The Cyrenellse wxre at first presumed to be confined to 

 Africa. Mr. Cuming, however, some yeai-s since, brought 

 home several species from the Philippines. Mi'. Deshayes, in 

 1853, described a fossil one, the Cyrenella hicinoides^ from the 

 basin of Paris, but ho has since seen cause to refer it to the 

 genus Diplodonta. 



The C. sahnacida and C. Atnericana are very rare shells. 

 Mr. Cuming has one of the former in his cabinet; but, with 

 that exception, Mr. Morelet is, I believe, the only person who 

 has specimens of them. 



In order to make these species better known, I have thought 

 it would not be amiss to append a copy of Mr. Morelet's descrip- 

 tion of them, accompanied by drawings, which I have been 

 enabled to procure through his kindness. 



