168 MR. J. Y. JOHNSON ON NEW GENERA AND SPECIES [June 10, 



front. The vent is in the hinder half of the body, and about yg-th 

 of the total length behind the middle. The anal fin commences 

 within a short distance of the vent ; it is very low in front, where it 

 is cloaked by thick skin, and where there is a furrow at each side of 

 and parallel with its base ; further behind there are two parallel 

 furrows. The tail is compressed, the fin narrow and rounded. All 

 the fins are covered with a thick skin. 



Although several specimens of this Eel have been obtained (some 

 of which have been sent to the British Museum), it must still be con- 

 sidered as a rare fish. In colouring it resembles Thyrsoidea unicolor, 

 Kaup, from which it differs generically in the uniserial dentition. 



The following measurements were taken from a specimen having 

 a total length of 40f inches, with a depth, near the gill-openings, of 

 3^ inches : — 



Inches. 



Rictus 2-/^ 



Gill-openings, distance from snout 5 



Vent, distance from snout 221 



Dorsal fin, distance from snout 4|- 



In another specimen, 36|- inches long, the longer axis of the eye 

 measured -f-^ inch, and the longest teeth were less than ^th of an 

 inch in length. The rictus was l^^^^inch in depth. 



Thyrsoidea atlantica, sp. n. 



Anguilliform, compressed ; attenuate both ways from middle of 

 body. Skin smooth, scaleless, white, with one dusky oval blotch on 

 one side of body, and two or three such blotches on the other side, 

 unsymmetrically placed. The longer axis of these blotches is from 

 one-third to one-half an inch across. On the fins near the posterior 

 extremity of the body are several similar blotches. 



A single specimen of this Eel has occurred, the dimensions of 

 which are embodied in this description. 



Total length 23 inches ; depth ly^ inch, taken about an inch in 

 advance of the vent. 



Head compressed, rising behind the eyes ; depth through head 

 and swollen throat, ly^ inch. Eyes covered with skin, placed a little 

 in advance of the middle of the upper jaw, rather less than one-fifth 

 of an inch in diameter. Plinder nostril-tubes shorter than anterior, 

 placed a little in front of the vertical from the anterior orbit of eye. 

 Front nostril-tubes reaching a little beyond lip. Mouth cleft rather 

 more than an inch deep. Jaws rather slender, somewhat curved, 

 and not capable of shutting closely on account of the length of the 

 front teeth and the curvature of the jaws. Lower jaw a little longer 

 than the upper, without a barbel. Teeth in both jaws slender, 

 pointed, somewhat compressed, curving backwards. In the upper 

 jaw there are two rows at each side, those of the inner row being 

 longer. A row of seven teeth along the middle of the palate. The 

 longest teeth in the jaw are rather more than one-fifth of an inch in 

 length. In the lower jaw there is a single row at each side ; in front 



