6n the occurrence or a new species op RHINOPTERA (R. 



ENCENADiE) IN TODOS SANTOS BAY, LOWER CALIFORNIA. 



By ROSA SITIITH. 



In the year 1882, Miss Fanny E. Fish, then residing near Encenada, 

 Lower California, found, on the beach near that place, one jaw of hex- 

 agonal teeth which evidently beloDg to a species of EMnoptera. The 

 teeth were sent to me for identification and have now been presented 

 by me to the TJ. S. National Museum. 



It is a lower jaw and has fourteen series of hexangular teeth, the sin- 

 istral outer row nearly twice as broad as the narrowest iuner series, the 

 dextral outer series a little broader, just equaling two of the narrowest 

 series and one and a half times broader than loug. The teeth of the 

 two sides of the jaw differ from each other. Inside the siuistral outer 

 series are four rows of smaller teeth, as broad as long, nearly uniform iu 

 shape and size, the width of the four rows collectively equaling one 

 and two-fifths times the width of the series of the broad teeth just inside 

 them ; the teeth in this row are the broadest of the jaw and about twice 

 as broad as long. The seventh sinistral series has teeth that are some- 

 what enlarged, two-thirds the diameter of the sixth and widest series 

 just described, scarcely broader than long. Inside the dextral outer 

 row are two rows of enlarged teeth, slightly larger than the seventh 

 sinistral series ; immediately inside these are three rows of narrow teeth, 

 similar to the four rows of small teeth next the siuistral marginal row; 

 the seventh dextral row and the central series contain small teeth that 

 coalesce into a single row a little back of the center of the jaw. The 

 jaw anteriorly has fifteen series of teeth, and jjosteriorly onl^' fourteen, 

 by the coalescence of the teeth of the central and seventh dextral series, 

 as above stated. 



The jaw is weather-worn, and has lost a few of the teeth, including 

 both its front and back margins. 



This jaw can only belong to a species of Rhhwptera , and among the 

 described si)ecies the only one which closely approaches it is EMnop- 

 tera polyodon Giinther, based on a pair of jaws of unknown origin. 

 From the latter it differs in being somewhat unsymmetrical, the broad- 

 est series of teeth being the sixth (from one side, eighth from the other), 

 and also in having the teeth iu smaller number (fourteen rows instead 

 of nineteen.) 



It is probable, therefore, that the jaws from Todos Santos belong to a 

 distinct species, which I may name Rhinoptera encenadce. 



San Diego, Oal., November 20, 1885. 



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