HISTORY OF THE AMERICAN MENHADEN. 21 



thought it desirable to name provisionally two varieties, and to call 

 attention to others which may possibly exist. This is done with much 

 hesitation, and only wiih a view to an attempt to formulate the minor 

 dili'ereuccs to be observed between fish of the same species on different 

 parts of our coast. A precisely parallel case is to be found in the shad 

 of the different Atlantic rivers, which are well-known to exhibit strong 

 distinctive marks. Very possibly every school of menhaden has its own 

 characteristics. In every case where I have had an opportunity to 

 observe them, the individuals composing the same school were closely 

 similar to each other. 



The typical form of the species, as now defined, is taken from the coast 

 of Southern New England and the Middle States. It has the height of 

 the body about oue-third of the total length, the head three-tenths of 

 the total length, or a little more; the maxillary long (.14 to .14^), and 

 exceeding the height of the dorsal. 



The species described by Spix, under the name of Clvpanodon mireus, 

 cannot be distinguished by any apparent specific characters from Bre- 

 vooriia tyrannns, since one or more of the specimens of the latter species 

 before me partakes of some of the peculiarities of the Brazilian form. 

 There is, however, a general average of character exhibited by tLe Bra- 

 zilian specimens, as well as the figure of Spix, with which they closely 

 agree, which seems to me to entitle them, for the present at least, to 

 recognition as belonging to a distinct geographical race. The dis- 

 tinctive characters appear to consist in (1) a greater average height of 

 body ; (2) a lesser length of head ; (3) a lesser average length of maxil- 

 lary and mandible; (4) a slightly lower anal and dorsal fin; (5) a greater 

 average distance of anal from snout; (C) a greater average length of 

 the medial caudal rays; (7) a shorter average length of pectoral; (8) a 

 more regular arrangement of the scales, and a more luxuriant growth 

 of small scales at the basis of the fins. 



A number of specimens Irom Noank, taken in 1874, vary quite as 

 much from the normal type, and in almost the same respect as the vari- 

 ety just described. The maxillary and mandible are shorter, however, 

 than in the Brazilian form, the anal fin lower and the lobes of the cau- 

 dal are extremely short, sometimes hardly exceeding in length the pec- 

 toral fin. But for the fact that these specimens show almost all the 

 characters of the Brazilian Brevooriia, and in some cases exaggerations 

 of them, I should be inclined to consider the aurea a distinct species. 

 Having with some hesitation allowed to this the rank of a subspecies, 

 the question must be decided as to the propriety of also allowing sub- 

 specific rank to this peculiar form from Noank. The exact meaning of 

 the terms subspecies and variety, as recently employed by zoologists, is 

 not very clear to my mind, but I infer a " subspecies " to be composed of 

 an assemblage of individuals varying uniformly from the typical spe- 

 cific forms in a degree sufficient to be susceptible of description and 

 definition, though not necessarily separated from it by the absence of 



