Miscellaneous. 185 



There is a good deal of difference in the shape and form of the 

 blade bone, probably dependent on age. Tbe blade bone of the 

 smaller specimen is subtriangular, being about one 10th part 

 wider than it is high from the front of the condyle to the upper edge ; 

 the acromion and coracoid processes are directed forwards, and 

 only slightly bent outwards ; the acromion is much broader, and 

 rounded at the end. In the larger specimen the blade bone is 

 much wider than high ; that is to say, it is more than once and a 

 half as wide as high ; the coracoid and acromion processes are 

 much elongated and strongly bent upwards. This difference may 

 be sexual ; for the young bone does not appear to be like a portion 

 only of the larger one : and if there is a change of form, the whole 

 bone changes as it grows ; that is to say, the angular prominence 

 on the front edge is lower down the front margin in the larger one. 



In all these specimens the bones of the face are shorter than the 

 distance from their edge to the crest round the nostrils ; and in 

 this respect it differs from De Blainville's figure of Physeter breviceps, 

 which is said to have come from the Cape of Good Hope ; but I 

 have never had the opportunity of examining the skull, and there- 

 fore cannot vouch for the correctness of the figure. 



A partial Comparison of the Conchology of Portions of the Atlantic 

 and Pacific Coasts of North America. By Robert E. C. Stearns. 



A striking feature in the conchological fauna of that part of the 

 Pacific coast included in the Californian- and- Vancouver zoological 

 province, when compared with the molluscan fauna of the Atlantic 

 coast from the arctic seas to Georgia, is the preponderance in the 

 former of those forms of molluscan life which are embraced in the 

 order of Scutibranchiata*. 



The Scutibranchiate Gasteropods, or shield-gilled crawlers, com- 

 prise a great number of mollusks, all of which are marine, and which 

 inhabit the sea-shore, principally the littoral and laminarian zones, 

 subsisting on marine vegetation ; thus we find the beautiful group of 

 Calliostoma upon the larger algae, as well as the unique Trochiscus (T. 

 Sowerbyi), and Chlorostoma crawling over the sedimentary rocks, 

 upon which grows the green Cladophora or some allied vegetable 

 form upon which it feeds, and which also is the favourite food of 

 several species of limpets. 



The order of Scutibranchiata, according to Messrs. Adams, in- 

 cludes : — the family of Neritidas (none of which are found in the 

 Californian and Oregonian province, though they begin to appear on 

 the coast of Lower California) ; the Trochidoj, which is largely re- 

 presented by the following genera — Eutropia one species, Leptothyra 

 three species, Pachypoma and Pomaidax one species each, Liotia one 

 (perhaps two) species, Thalotia and Trochiscus one species each, 

 Calliostoma, Chlorostoma, Omphalius, Margarita, and Cibbula, each 

 by several species ; the family of Haliotidas, which is represented by 

 several species, all of large size, widely distributed and exceedingly 

 numerous in individuals — Fissurella, including Lucapina, Glypliis, 



* Vide Adams, ' Genera of Recent Mollusca,' vol. i. p. 376. 

 Ann. & Mag. N. Hist. Ser. 4. Vol. xii. 13 



