368 MESSRS. MACDONALD AND BARRON [May 28, 



among the most fortunate of recent carcinological observations. 

 Their great size would well adapt either of the species for culinary 

 purposes if any one could be induced to acclimatize the species to 

 our own lakes and streams. This appears to be the more easy in 

 regard to the species from America, since the Lake Amatitlan is at so 

 lofty an elevation as to be of a very low temperature. 



DESCRIPTION OF PLATES XXX. & XXXI. 



Plate XXX. 



Macrohrachium americanum. c. Rostrum, b. Superior antennae, c. Inferior 

 antenna, d. Mandible, h. First pair of pereiopoda. v. Posterior pair of 

 pleopoda. z. telson. 



Plate XXXI. 



Fig. 1. M. formosense. c. Scale of inferior antennee. v. Posterior pair of 

 pleopoda. z. Telson. 



2. M. longidigitum. c. Scale of inferior antennee. v. Posterior pair of 



pleopoda. z. Telson. 



3. M. africcmum. c. Scale of inferior antennte. v. Posterior pair of 



pleopoda. z. Telson. 



5. On a supposed new species of Galeocerdo from Southern 

 Seas. By J. D. Macdonald, M.D., F.R.S., and Mr. 

 Charles Barron^ Curator of the Haslar Museum. 



(Plate XXXII.) 



The following observations on a species of Galeocerdo, from the 

 Australian coasts, are based on two jaws and a portion of skin pre- 

 served by F. M. Rayner, Esq., Staff-Surgeon, E.N., together with 

 notes and measurements made by him, and drawings made by Dr. 

 J. D. Macdonald, R.N., from the recent animal. 



On reviewing the literature of the genus Galeocerdo it would ap- 

 pear that, comparatively, few specimens have actually been obtained 

 for scientific examination, as the great authorities on this group of 

 fishes, Miiller and Henle, only mention two examples of the southern 

 Tope (G. tigrinus), and two of the northern (G. arcticus), with seve- 

 ral jaws ; and the British-Museum Catalogue of the Chondropterygii 

 only includes one specimen of the former and three jaws of the 

 latter species. 



When we compare the external characters of the two known 

 species, as given and depicted by Miiller and Henle, with those of 

 the present Shark, we find the proportions of the body and fins of 

 G. arcticus (Miiller and Henle, pi. 24) to agree best with it ; but in 

 the colour of the skin there is great difference, and the scales repre- 

 sented in the plate alluded to are approximated and slightly imbri- 

 cated, besides being relatively broader and more distinctly three- 

 keeled than those of our fish. Moreover, although the teeth figured 



