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ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



spines before the dorsal and anal fins, and which, by virtue of this character, 

 though in the case of the former the spines are not apparent externally, serve 

 manifestly to re-conduct to the section to which Lichia belongs. The discovery 

 of the present genus, therefore, furnishes a more completely connecting link 

 between these two groups. 



Rhynckobdella and Mastacemblus agree with Paropsis, both in wanting 

 ventrals and in having the first dorsal represented by free spines ; but the form 

 of these two genera is so totally different in all other respects, that it is impossible 

 they can be confounded with it. 



This new genus is from the east coast of South America. 



Paropsis signata. Jen. 



Plate XIII. 



P. argenlea, nitens, summo dorso ccerulescente ; operculo ad angulum superiorem 

 macula nigra signato ; pinnis pectoralibus maculis duabus in axillis et ad radices 

 radiorum, minor ibus. 



B. 10 ; D. 5—1/33 ; A. 2—1/35 ; C. 17, et circa £ accessar. ; P. 21 ; V. 0. 



Long. unc. 9. 



Form. — Body very much compressed, of a rhomboidal form, the dorsal and ventral lines rising to an 

 angle at the commencement of the dorsal and anal fins respectively. Head a laterally com- 

 pressed cone : tail becoming suddenly attenuated before the setting on of the caudal fin, with- 

 out any keel at the sides. Back sharp and elevated ; the greatest depth contained not more 

 than two and a half times in the entire length : thickness only one-fifth of the depth. The 

 length and depth of the head are equal, each being half the depth of the body. The upper and 

 under profile meet at the extremity of the snout at nearly a right angle, the former falling in a 

 very regular curve from the commencement of the dorsal fin. Mouth moderately large, the 

 commissure reaching to beneath the eye, with the lower jaw projecting and of considerable 

 strength and thickness. In each jaw a single row of very fine sharp teeth. The tongue, which 

 is of a triangular form, free at the tip, and pointed, is rough, with some extremely fine closely 

 shorn velutine teeth : a small triangular patch of these last teeth on the front of the vomer, and 

 a narrow row on each palatine : pharyngeans with rather stronger teeth. The intermaxillary is 

 very slightly protractile. The maxillary reaches, when the mouth is closed, to a vertical from 

 the posterior part of the orbit : it is very visible from without, having only its anterior portion 

 concealed by the suborbital, and being much dilated at its posterior extremity, which is in 

 shape somewhat securiform. Eyes above the middle of the cheek, and nearer the end of the 

 snout than the posterior margin of the opercle; their diameter rather more than one-fifth the 

 length of the head: the suborbital forms a narrow band beneath each. Nostrils half-way 

 between the eyes and the end of the snout ; the anterior orifice round ; the posterior, which is 

 the larger one, oval. Preopercle with the ascending margin nearly vertical ; the angle at bot- 

 tom rounded. The opercle and subopercle together present a rounded margin posteriorly, 



