150 Miscellaneous . 



the superintendent of the works, by whom the specimen was kindly 

 submitted to the writer for description. The specimen is in the 

 museum of the Newcastle Mechanics' Institute. The anterior part, 

 to beyond the pectoral fins, is wanting. Length of part preserved 

 12 inches ; width 2| inches ; near base of caudal fin 1 inch. 



Helicerus (nov. gen.). — Allied to Belemnites. Calcareous ossicle 

 thick, subcylindrical, containing internally a slender tubular cavity, 

 (a continuation probably of an alveolus above,) which terminates in 

 a small fusiform chamber helicoidly divided. This chamber has the 

 shape of two cones put base to base ; the tube leading to it appears 

 to have contained a rolled membrane to correspond with the turns 

 of the spiral dissepiment in the fusiform chamber. 



Helicerus fuegiensis. — Ossicle cylindrical, half an inch in diameter ; 

 diameter of tube within nearly one-sixth that of the fossil, and that 

 of the chamber more than half the same. Texture of the ossicle 

 radiating fibrous, like ordinary Belemnites. Found by the writer in 

 a slate rock on the shores of Nassau Bay, near Cape Horn. — Silli- 

 man's Journal for May 1848. 



Notes on some Australian Fossils. By J. D. Dana. 



In the valuable article by F. M'Coy on the fossils of Australia 

 (Ann. Nat. Hist. vol. xx. p. 145), which was published some months 

 after the writer's article on this subject, but before that article had 

 reached Mr. M'Coy, there are some species redescribed. We ob- 

 serve that 



Cardinia ? exilis, M'Coy, is Cardinia recta, D. 



Pleurotomaria Morrisiana, M'Coy, is Pleurotomaria trifilata, D. 



Pachydomus ovalis and P. pusillus, M'Coy, are species of Astartila, 

 D., a genus nearer Astarte than Pachydomus. 



Pachydomus sacculus, M'Coy, is a Eurydesma ; E. cordata ? of 

 Morris. (See Strzelecki's N. S. Wales, pi. 12. fig. 1.) 



The genus Notomya, M'Coy, corresponds to Pyramus, D., and 

 from the examination of our species, we cannot believe that they are 

 related to the Myida. 



The genus Mcconia of the author, (changed from Myonia,) along 

 with Pyramus, and probably Cleobis, make a natural group among 

 the Astartidce, having the smaller anterior muscular impression 

 facing in the same plane with the larger anterior, and thus differing 

 strikingly from Astarte, Pachydomus, Astartila, Cardinia. Moreover 

 the larger anterior is prolonged upward, and is pointed, towards the 

 smaller anterior muscular impression. Mceonia has a second small 

 anterior muscular impression, situated high up on the beak : if this 

 is not sufficient for a generic distinction, all the species may be 

 thrown together in the genus Mceonia, as the gradations are such 

 that it is difficult to draw lines of distinction. The Pachydomus 

 gigas of M'Coy falls into the same group, being between Cleobis and 

 Mceonia as these genera were before laid down. The group Cleobis, 

 if sustained, would include species not having the sides at all exca- 

 vate ; but this hardly seems to be a generic character among these 

 species. The Pachydomus globosus of Morris and M'Coy appears to 

 be a different species from the P. globosus of Sowerby, whose figure 



