1884.] NATURAL SCIENCES OP PHILADELPHIA. 229 



"Was taken at Key "West. This is precisely like the adult, but shows 

 very little blue. 



The species called Acronurus are, as shown by Giinther and 

 Liitken, the young of Teuthis. The three species mentioned by 

 Poey (cceruleatus, nigriculus, carneus) seem to be the young 

 respectively of three species of Acanthurus. One of these, Acro- 

 nurus carneus, was obtained by Prof. Jordan ; we regard it as 

 unquestionably the young of Teuthis hepatus. 



2. Teuthis tractus. 



Acantkurr/s tracfusToej, Memorias, ii, 1860, 208 (Cuba) ; Poey, Rept., 

 186G, 356 (Cuba) ; Poey, Syn. Pise. Cub., 1868, 356 (Cuba) ; Poey, 

 Anales Soc. Hist. Nat. Madrid, 1880, 246 (Cuba) ; Poey, Enum. Pise. 

 Cub., 1875, 67 (Cuba) ; Jordan & Gilbert, Bull. U. S. Fish Comm., 

 1882, 108 (Mazatlan ; no descrii tion) ; Jordan & Gilbert, Bu'l. U. S. 

 Fish Comm., 18S2, HI (Panama ; no description) ; Jordan& Gilbert, 

 Proc. U. S. Nat. Mus., 1882, 377 (Panama ; no description) ; Jordan 

 & Gilbert, Syn. Fish. N. A., 1882, 941. 



Acronurus nigriculus Poey, Enum. Pise. Cub., 1875, 69 (Cuba ; larval 

 form) . 



Acanthurus mafoides Jordan & Gilbert, Proc. U. S. Nat. Mus., 1882, 

 626 (Panama ; no description ; not of Cuvier & Valenciennes). 



Habitat. — Coasts of tropical America ; Cuba ; Panama. Key 

 West ; Mazatlan ; Panama. 



This species may at all ages be known by the form of its caudal. 

 Although in all species the caudal lobes grow longer with age, 

 still very young specimens, as well as old of this species have the 

 caudal more deeply furcate than any of T. hepatus. 



There are also some color differences between the two. 



The single species of Teuthis found on the Pacific coast of 

 tropical America seems to be identical with T. tractus. It is 

 close to A. matoides Cuvier & Yalenciennes, but Prof. Jordan, 

 who has examined the type of the latter in Paris, thinks it 

 different. 



3. Teuthis hepatus. 



Hepatus mucrone reflexo utrinque prope caudam Gronow, Zoophyl, No. 



353. 

 Teuthis hepatus Linnaeus, Syst. Nat., ed. 12, 1766, 507 (not as 



restricted by Cuvier & Valenciennes ; is based principally on Hepatus 



of Gronow). 

 Acanthurus hepatus Bloch & Schneider, Systema Ichthyol., 1801, 211 



(in part; not of Cuv. & Val. and later authors). 



