ATLANT. DEEP-SEA EXPED. 1910. VOL. III]. 



MURAENOID LARVAE. 



23 



As the had has become a little deformed in the 

 preserving fluid, I have not been able to ascertain the 

 position and form of the nostrils. As far as I can see 

 both of them are placed as represented in fig. 16. 



The alimentary canal is very thin and situated close 

 to the ventral contour of the animal. 



All the fins contain rays. The pectoral fin has 6 

 rays, which are quite indistinct. The caudal fin has 6 



Fig. 16. Head of L. spinocadux 



very powerful rays, U t and H 2 having each three. They 

 have a length of about 1-6 mm. 



Interspinous elements are developed in the margin 

 of the embryonic anal fin, but rays have not yet appeared 

 on the foremost ones. 



Proceeding backwards there are first feeble indications 

 of rays, then rays having distinct contours, and lastly near 

 the caudal fin very powerful rays. The last ray of the 

 anal fin is situated close to the lowest caudal fin-ray. 



In the dorsal fin too we see rays and interspinous 

 elements most strongly developed posteriorly. Proceeding 

 forwards the rays first become indistinct, then gradually 

 disappear, followed by a space with interspinous elements 

 decreasing in development towards the front, until they 

 are only indicated as a rather dark shadow in the margin 

 of the embryonic fin. 



The interspinous elements and rays of the vertical fins 

 form a very acute angle with the longitudinal axis of the body. 



As for pigment there is only one row of spots on 

 the anal fin, one little spot at the base of each ray. 



9. Leptocephalus polymerus n. sp. 



In his work "Leptocephalids in the University Zoo- 

 logical Museum at Upsala", Upsala 1896, (33) Stromman 

 describes a species which he calls L. curvirostris. As he 

 does not indicate the. number of segments it is impos- 

 sible to determine with certainty whether the two speci- 

 mens here described under the name L. polymerus really 

 belong to that species or to a very near ally. 



The smaller specimen, taken at the surface at Stat. 



51, is shown in fig. 5 on pi. Ill, arid the head is shown 

 in fig. 17 in the text. The larva is long in proportion 

 to height, body much compressed, decreasing in height 

 backwards, tail terminating in a very fine tip; anus situ- 

 ated far back; head comparatively small, snout pointed. 

 There are as yet no indications of rays or interspinous 

 elements in the fins, and the nostrils are not yet fully 

 separated (fig. 17). The larva is less fully developed than 

 the second and larger specimen taken at Stat. 52 in 50 

 metres. In the larger specimen the nostrils are separated 

 but placed close together; there are indications of a great 

 number of interspinous elements in the vertical fins, 

 whereas rays are still wanting; anus placed farther for- 

 ward on the body; teeth rather more numerous. 



The pigmentation of the larger specimen agrees with 

 Stromman's description of L. curvirostris a series of dots 

 running along the lower margin of the body directly over 

 the alimentary canal, and other series of dots following 

 the lateral line and the bases of the vertical fins. In the 



Fig. 17. Head of L. polymerus. 10 /i. 



smaller specimen we can see traces of a series of dots 

 which seem intended to run along the anal fin, whereas 

 the series along the dorsal fin is absent. 



Measurements of the two specimens are given in the 

 following table: 



Total length 208 mm 125 mm 



Distance from point of snout to 



anal aperture 190 „ 119 „ 



Distance from point of snout to 



foremost dorsal interspinous 



element 184 „ ? 



Greatest height 8 „ 6 „ 



Length of head 4-6 „ 4-0 „ 



Distance from point of snout to 



foremost margin of eye .... 2-3 „ 1-9 „ 



Largest diameter of eye 1-0 „ 0-8 „ 



Number of segments: preanal. 303 305 



: postanal about 140 >100 1 ) 



, : total . ... 443 > 405 



Number of teeth in one half of 



upper jaw 2 + 6 + 4 1+4+4 



Number of teeth in one half 



of lower jaw 1+5 + 5 1 + 4 + 4 



l ) Tip of tail damaged. 



