ATLANT. DEEP-SEA EXPED. 1910. VOL. 111]. 



MURAENOID LARVAE. 



27 



separated. The anterior one, which is becoming tubular, 

 is placed almost midway between the point of the snout 

 and the anterior margin of the eye, while the posterior 

 one, an oval aperture, is placed obliquely upwards from 

 the centre of the eye. 



In half of the upper jaw there are a front tooth (broken 

 off), followed by 8 teeth, of which the posterior 5 are 

 smaller and placed closer together. There are 6 slanting 



Fig. 24. Head of L. similis, station 64, 1000 metres. 1B /i- 



In regard to gill-opening, fins and pigment the two 

 specimens are identical. 



Comparing the two species L. euryurus and L. similis 

 with the known larvae of Muraena helena, described by 

 Grassi(16), many resemblances will be found. The general 

 appearance of the three species are the same; they have 

 all a short but high head, while the body terminates in a 

 rounded tail. Also the absence of pectoral fins is a feature 

 common for these three species. Judging from all this, 

 it is probable, that the two species described here have 

 parent forms which are nearly allied with Muraena helena. 

 Looking in the table p. 6, we find one species of the 

 family Muraenidae, whose segment-number corresponds to 

 that of L. euryurus viz. Echidna catenata Bleek. As I have 

 not had the opportunity of examining an adult Echidna, 

 I am unable to say if there is a connection between it 

 and L. euryurus, but deeming from the fact, that the 

 vertical fins in our larvae have very few but conspicuous 

 rays it seems more probable that they are the larvae of 

 some species of Muraena. 



teeth in each half of the lower jaw; the foremost tooth 

 is absent. 



The point of the lower jaw does not extend so far 

 forward as the point of the snout. 



The gill-opening is a very narrow slit. Pectoral fins 

 are totally wanting. It is only in the portion adjoining 

 the caudal fin that the vertical fins contain rays and inter- 

 spinous elements. The caudal fin contains 4 rays, Hi and 

 H 2 having two each, The rays of the vertical and caudal 

 fins are quite short and especially in the vertical fins, 

 they are rather wide apart. 



As for pigment there are only a few spots on 

 the brain portion (see tig. 23) 



Specimen no. 2 is a little larger, 40 mm long, 

 maximum height 6 mm. It may possibly represent a 

 somewhat later stage of development, as the head 

 is of a rather rounded form (see fig. 24). Also in 

 this larva the anus is placed midway between the 

 point of snout and the tail-tip, 21 mm from the point 

 of the snout. There are 55 preanal and 55 postanal 

 segments, 110 in all. 



Length of head 2-7 mm, greatest height 2-1 mm, 

 distance from point of snout to anterior margin of 

 eye 1-1 mm. 



The shape and number of teeth are shown in 

 fig. 24. The foremost tooth of the upper jaw (which was 

 broken off in specimen no. 1) is in no. 2 thin and straight. 

 The foremost tooth of the lower jaw (also wanting in no. 1) 

 is curved. The greatest diameter of the eye is 0-6 mm, 

 the horizontal diameter being 0-5 mm. 



15. Leptocephalus proboscideus n. sp. 



The larva under consideration, taken at Stat. 53 in 

 150 metres, is one of the most peculiar in the collection. 

 Its appearance is shown in fig. 1, pi. V, and we see that 

 it is specially characterized by its snout, which is prolonged 

 into a rather flexible proboscis; it is partly broken off, 

 and has certainly been much longer. The head has an 

 extraordinary appearance, as shown in fig. 25, the upper 



Fig. 25. Head of L. proboscideus. 16 /i. 



contour forming a rather acute curvature in front of 

 the obliquely directed telescopic eye. The pigmentation 

 furnishes a third characteristic feature distinguishing this 

 larva from similar species. Along the lateral line there 

 are 4 or 5 subcuticular double spots, seen in fig. 1, pi. 



