FAMILY TRIGLIDJE. 49 



GENUS DACTYLOPTERUS. Cuvier. 



The pectoral fins excessively developed, and composed of two portions, forming a large fin 

 which serves as a tving. Head fiat, granulate. Body covered with hard carinated scales. 

 Preopercle armed with a long spine. Ventrals with hut four soft rays. Teeth in the 

 jaivs, but not on the vomer or palatines. 



Obs. This genus, as now restricted by Cuvier, comprises but two species ; one from the 

 Indian ocean, and the other known from the earliest antiquity, and common in the Mediterra- 

 nean sea. This latter is also found along the shores of South America, and is not uncom- 

 monly brought by the gulf stream along our coast as far even as the Banks of Newfoundland. 



THE SEA SWALLOW. 



Dactylopterus volitans. 



PLATE XVII. FIG. 46. BiCK OF the he.id and scales enlaroed. — (STATE COLLECTION.) 



Trigla volitans. LiN. p. 498. 



Morcielago. Parra, Descn'pcion, &c. p. 25, pi. 14. 



Polynemus sexradiatus, MiTCHiLL, Mem. pi. 4, fig. 10. Supplement Month. Mag. Vol. 2, p. 323. 



Le Dactyloptere commun, D. volitans. CuV. el Val. Hist. Poiss. Vol. 4, p. 117. 



Characteristics. First ray of the dorsal slightly longer than the succeeding ; a short triangular 

 crest between the first and second dorsals. Length six inches. 



Description. Body cylindrical, tapering towards the tail. Head cubical or four-sided, wider 

 than high. Length of the head, to the total length, as one to five. Body covered with rough 

 solid scales, dentate on their free margins, and with a prominent crest on each, which is finely 

 toothed (see figure). These crested scales become effaced on the abdomen. They are evi- 

 dent on the back, but become most conspicuous in five or six rows along the flank, which 

 gradually coalesce, the upper and under row becoming more and more elevated, until they 

 terminate in two highly crested plates on each side of the tail. Sixty-five scales are enume- 

 rated from the opercle to the tail, and thirty-four from the dorsal to the centre of the abdomen. 

 Head broader than high, flattened above with a broad furrow between the orbits, descending 

 nearly vertically in front ; the whole helmet being covered with deep granulations. The 

 suborbital bones advance, and nearly approach in front, their whole margins being strongly 

 crenated ; posteriorly they terminate in two points, with a broad emargination between them ; 

 the one above forming a portion of the orbit ; the other beneath longer and more acute, termi- 

 nating at the inner angle of the preopercle. The preopercle terminates in a long stout spine, 

 which extends beyond the base of the pectorals, with a prominent ridge on its surface, fur- 

 nished with teeth directed forwards ; its lower margin is likewise dentate. The sur-scapulars 

 terminate on each side above in a very robust broad spine, which reaches as far as the penul- 

 timate ray of the first dorsal (see figure). On the surface of each spine is a strong crenate 



Fauna — Part 4. 7 



