edge of the jaws; the exterior granular or short villiform 

 stripe, if it exists, being invisible to the eye, aided by a 

 good lens. The teeth on the chevron of the vomer and 

 edges of the palate bones are more distinct than those on 

 the jaws, and form a broader line, as if there were two or 

 three rows. No granular patches can be discovered on the 

 disk of the palate bone. 



Length, 2| inches. 



Hab. The Southern Atlantic and Australian Oceans. 



Myctophum asperum. Richardson, 



Cii. Spec. Mycl. compressum, caudd gracili, superne post 

 phniam udiposam plana ; rirtii oris grmidlusculo pa- 

 rum ultra ocuhiin mo</nH)n ^fisso ; apparatu lucido 

 e narihus in medium spatium interocularein extenso ; 

 allitudine corporis quintam partem longitudinis totius 

 (squanti; squamis eroso-denticulatis. 



Radii:— D. 14; A. 18; C. 19|; P. 16; V. 8. 



Plate XXVII., figs. 13, 14, 15. 



Profile very obtuse in front. Shoulders not so much 

 compressed as those of Alyct. coruscans ; their thickness 

 is about half their height, which again is equal to about 

 one-fifth of the total length. The length of the head is 

 greater than the height of the body. The eye is large, 

 and is more than its own diameter removed from the gill- 

 opening, being near the profile of the snout. Its diameter 

 is contained two-and-a-half times in the length of the 

 head. The large gape passes a little beyond the eye, and 

 the preoperculum inclines slightly backwards. 



Minute setaceous teeth form an even row on the margin 

 of both jaws, and by the help of a lens, two or three rows 

 of very minute acute teeth may be seen on the conve.x 

 surface, exterior to the principal row. The same micro- 

 scopical teeth are seen, but much less distinctly, on the 

 upper jaw. Several rows of setaceous teeth are visible to 

 the naked eye on the chevron of the vomer and edges of 

 the palate bones, and a patch of granular microscopical 

 teeth covers the convex plate of the palate bones. 



The shining apparatus reaches from the middle of the 

 orbits forward to round the nostrils. It is supported by 

 thin plates of bone, which rise from the os frontis, and by 

 others which form cells in the nasal regions ; there is also 

 a low mesial keel between the nostrils. 



The ventrals are attached well before the middle of the 

 fish, being midway between the snout and end of the anal 

 fin. The dorsal commences over them. 



The lateral line contains thirty-seven or thirty-eight 

 scales, which are slightly toothed on the exterior edge. 

 The other scales are more deeply toothed, the teeth being 

 readily visible to the naked eye, and rendering the fish 

 rough to the touch. [Vide figs. 14 and 15). 



The opal or pearly dots are distributed as in the two 

 species already mentioned, except that there are only four- 

 teen above the anal fin, exclusive of the usual two on the 

 lower base of the caudal fin. 



Length, If inch. 



Hab. >. 



Myctophum hians. Richardson. 



Ch. Spec. Myct. ore laxissimo ; pinnd dorsi post ven- 

 trales incipienti ; pinnd ani longd ; allitudine corporis 

 quintam partem longitudinis totius aquanti ; caudd 

 gracillimd, elongatd. 



Radii. — D. 14; A. 22; C. 22; P. 15; V. 8. 



Plate XXVJI., figs. 19, 20, 21. 



This species has a gape as wide as Lampanyclus, and 

 the dorsal placed farther back than is usual in Myctophum, 

 with a longer anal. It possesses the common clavate out- 

 line, with an obtuse forehead, and very slender tail. The 

 height of the body equals one-fifth of the total length, 

 caudal included. The short dorsal stands between the 

 ventrals and anal, and the top of the tail, behind the 

 minute adipose fin, is flattish, and exhibits a row of bright 

 specks laterally, corresponding to the number of the scales 

 that cover it. The anal fin is proportionally long. 



One half of the gape is behind the eye, and the preoper- 

 culum has a corresponding inclination backwards. The 

 maxillaries are very slender, with merely a slight oval 

 dilatation at their ends. Teeth on the jaws subulate, 

 slender, and acute; three rows on the lower jaw, and two 

 on the intermaxillaries. There is not much difference in 

 their height, but the row which is on the edge of the jaw 

 appears taller when held up to the light. There is a single 

 row on the edge of the palate bones, like those of the jaw, 

 and two or three irregular rows of granular teeth at its 

 base. None were discovered on the chevron of the 

 vomer. 



The scales of the lateral line are narrower, higher, and 

 more numerous than in the other species, being forty-one, 

 and there is only one complete row above them, while in 

 the preceding Myctophi there are two. The rest of the 

 scales are roundish, with the base less curved, and crossed 

 by four or five furrows. (Fig. 20, 21.) 



I am unable to describe the shining apparatus on the 

 forehead, the jaws having come away while the specimen 

 was in the artist's hands, before I had properly examined 

 them. There seemed to be, however, a small mesial crest 

 between the eyes, and anotlier between the nostrils ; and 

 it is probable that the glandular matter was deposited on 

 each side of them. The top of the tail between the adi- 

 pose fin and caudal is flat, and is covered with a nacry 

 matter. 



There are nineteen bright opal dots over the anal, two, 

 as usual, on the lower base of the caudal, and the others 

 which we observe in the rest of the Oceanic Myctophi. 

 Length, two inches. 



I examined the intestines of one of the small specimens, 

 but it was too much decayed for me to ascertain the spe- 

 cies. The gullet is narrow, below which a wider cyhn- 

 drical tube descends, to unite with an ascending pyloric 

 branch of equal size. More than half the length of the 

 stomach lies beneath their junction, in form of a conical 

 sac, which was very dark-coloured, from its contents. 

 The gut, on the contrary, is thin, delicate, transparent, 

 and slightly puckered, but not convoluted. There are 

 about six pyloric caeca, of unequal lengths. The air- 



G 



