ACADEMY OF NATURAL SCIENCES 175 



was found to be 117 - 117£°; and that between edge 1: /and edge 1 : 1 (which 

 equals ii on li, both unobserved planes) 95°-95J° : whence : It would equal 

 approximately 147° 30 / . The inclination of the rough plane r on the edge 

 1 : 1 is about 110°, but varies much. 



The results of calculation, taking as data the above mentioned angles I: I 

 and 1 : ii, along with the inclination of to U= 117° 15', and that of the 

 edge 1 : I (or It) to «= 95° 15' are as follows : 



C (= : ii) = 117° 15' and 62° 45' 



a (vert, axis) : (clinodiag.) : c = 0.5396 : 1 : 2.614 



1:1 = 156° 46' -1 : -1 (unobserved planes) = 164° 22' 



The species is related in form to Vivianite, in which 



a : b : 2c = 1.0792 : 1 : 2.614. 



The crystals of the two species are also alike in the perfect and pearly clino- 

 diagonal cleavage. 



On new Californian Marine Shells. ]Vo. II. 



BY PHILIP P. CARPENTER, PH. D., OV WARRINGTON, ENGLAND. 



Genus Collonia, Gray, 1852. 



This genus was established (in English) by Dr. Gray, for Turbinate shells 

 having an " operculum circular, with many gradually enlarged whirls, with a 

 convex external rib and central pit.'' Tlie type (still appearing as such iu the 

 B M. Col.) is a smooth fossil from Grignon, = Delphinula marginata, Lam., 

 with a keeled and crenated umbilicus, like Phillippia. Another (African) 

 shell is joined to the diagnosis, with the following brief description: " C. 

 striata, Gray. Shell red, white marbled, striated." It is quoted by Phillippi, 

 Handb. Oonch. p. 206, who assigns as a type T. sanguineus, Linn. For this 

 species and its congeners, we now propose a subgenus Leptonyx, as they do 

 not agree with the type. The genus was reconstituted by Messrs. Adams, 

 Gen. i. 396 for shells with "imperforate axis and contracted aperture:" the 

 description of the operculum being copied from Gray. The type is now "C. 

 marginata, Nutt." pi. 44, f. 2, the operculum of which is figured as with/ew> 

 whirls. The same description and figure are given in Chenu, Manuel i. 348, f. 

 2560. The error seems to have arisen thus. Mr. H. Adams (who acted for the 

 'firm' during his brother's long absence in Japan,) probably took Gray's C. 

 marginata to be the ' Turbo marginatus, Nutt.' of Reeve, and from tliis species 

 as type, described the genus to be imperforate, etc. Unfortunately, Dr. Gray 

 did not observe the error, which had arisen from confounding two different 

 shells called margbiatus ; and in his guide to Mollusca (in loco) he adop's the 

 description of Messrs. Adams; so that Collonia, Gray, (hodie) = Collonia, 

 Add., but not Collonia, Gray, (olim). Of the species arranged by Mr. H. 

 Adams under Collonia, some may belong to the original genus : some are in- 

 cluded under Cynisca, A. Ad.; and one (Turbo phasianella, C. B. Ad.) appears 



