ATLANT. DEEP-SEA EXPED. 1910. VOL. IIll. 



MURAENOID LARVAE. 



29 



pigmented groups, each consisting of four spots (two on 

 the ventral median line with one on each side of the 

 alimentary canal) forming a sort of cross, finally there are 

 two chromatophores near the anus, one on either side of 

 the alimentary canal. This arrangement holds good for 

 the two smaller larvae, and also for the larger larva except 

 on one point: the hindmost spot in each of the seven 

 groups of four chromatophores has disappeared, so that 

 each group consists of only three spots, one ventral 

 succeeded by two lateral. 



These differences, taken together with a relatively 

 larger head and a relatively larger trunk, justify me, I think, 

 in separating L. dolichorhynchus from L. proboscideus. 



The three larvae have not progressed beyond their 

 prelarval state, and are devoid of every trace of inter- 



Fig. 26. Head of L. dolichorhynchus, spec. 1. 15 /i. 



spinous elements as well as of true rays in the vertical 

 fins. Neither are true rays to be seen in the pectoral fins 

 which are present in the form of fan-shaped lobes with 

 a fine striated structure; neither do we see distinct traces 

 of hypural bones in the two smaller larvae, though in the 

 larger larva these bones have commenced to form, but 

 without the slightest trace of rays. The nostrils are 

 not separated in any of the larvae, their position being 

 indicated by an oval groove situated far in front of the eye. 

 The following table gives some measurements of the 

 three larvae, the total length being measured from the 

 point of the proboscis to the tip of the tail. 





Specimen 



Specimen 



Specimen 





1 



2 



3 





31 mm 



? mm 



42 mm 



Tip of tail to point of lower jaw. . 



24 „ 



24 „ 



33 „ 



Height 



4 „ 



4-0 „ 



4-8 „ 



Anus 



16 „ 



17 „ 



22 „ 



Head 



2-1 „ 



2-1 „ 



2-9 „ 



Snout 



0-9 „ 



0'9 „ 



1-2 „ 



Specimen 1 has 61 preanal and 67 postanal segments, 

 128 in all. It has 5 teeth in each half of the upper jaw, 

 the foremost one being broken, the remaining four small, 

 thick, and directed almost vertically. Each half of the 

 lower jaw is provided with 8 teeth, the foremost slightly 

 curved and directed almost straight forwards, succeeded 



firstly by two large teeth, and then by five small straight 

 ones, all directed obliquely forwards. Fig. 26 shows the 

 shape of the head and its pigmentation, but besides the 

 pigment indicated in the figure there is some pigment 

 covering nearly 1 mm of the proboscis, beginning about 

 2 mm from the base. 



Specimen 2 has 73 preanal and 59 postanal segments, 

 132 in all. In each half of the upper jaw there are 5 teeth, 

 and in each half of the lower jaw 7, the foremost being 

 slightly curved, followed by two large straight ones and 

 then four small ones. The head in its main features 

 resembles that of specimen 1, and so does the pig- 



Fig. 27. Head of L dolichorhynchus, spec. 3. 15 /i. 



mentation, though the anterior of the two spots on the 

 brain portion is absent. 



Specimen 3 has 75 preanal and 61 postanal segments, 

 136 in all. Several features in this the largest individual 

 prove that it is more fully developed than the other two. 

 Hypural bones have commenced to form, the brain is 

 distinctly more differentiated (see fig. 27), the teeth have 

 increased in number, and the profile of the head has 

 altered somewhat. The dentition consists of 7 or 8 teeth 

 in each half of the upper jaw, and 9 teeth in each half 

 of the lower jaw, the form and size being indicated in 

 fig. 27. 



The nostrils have advanced somewhat downwards, 

 but show no indication of separating. 



The pigmentation of the head is in its main features 

 like that in the other specimens, though the pigment on 

 the brain-portion is arranged rather differently. 



17. Leptocephalus stylurus n. sp. 



Six specimens of this species were taken at the same 

 station (no. 39), and in the same net (at 150 metres), 

 including representatives of different developmental stages. 



As shown in fig. 3 on pi. V this species is distinguished 

 by the lowness of the body in proportion to its length. The 

 body decreases gradually in height anteriorly and posteri- 

 orly, the tail is pointed, the head is low in proportion to 

 its length, and the eye is large. 



