ATI. ANT. DEEP-SEA EXPED. 1910. VOL. Ill] 



MURAENOID LARVAE. 



13 



by small interspaces. On the caudal fin there are very 

 small pigment-spots invisible to the naked eye. 



The anal is placed far back, 34 mm from the point 

 of the snout. 



The next specimen in point of size (no. 2) is 47 mm 

 long, resembling no. 1 in all essential particulars; the first 

 traces of interspinous elements can, however, be seen along 

 a larger portion of the edges of the vertical fins. The 

 caudal fin contains 17 rays, U 1 eight, and H 2 nine. There 

 are 106 preanal and 46 postanal segments, 152 in all. 



In all these prelarvae there is a large open interspace 

 between the anal aperture and the foremost indications 

 of interspinous elements of the anal fin. 



Specimen no. 7 is a fully developed larva 99 mm in 

 length which corresponds perfectly to the description given 

 by Schmidt of this stage. It has many relatively week 

 teeth in both jaws, and rather widely separated nostrils. 

 The rays of the pectoral fin are distinct, and those of the 

 vertical fins and the caudal fin are strongly developed 

 (the caudal fin having 17 rays, H^ eigth, H 2 nine). It 



Fig. 6. Head of larva no. 4. 



The next specimen (no. 3) has a length of 50 mm, 

 with 102 preanal and 44 postanal segments, 146 in all. 

 Dentition and nostrils resemble those of nos. 1 and 2. 

 The pectoral fin has no rays. In the vertical fins we find 

 a more advanced structure of the interspinous elements, 

 which can be traced farther forward than in nos. 1 and 

 2; the caudal fins, however, are exactly alike, provided with 

 the same number of rays, Hi bearing eight, and H2 nine. 



Specimen no. 4 has a length of 51 mm. It has 105 

 preanal and 42 postanal segments, 147 in all. The nostrils 

 are not yet separated, but we find an hour-glass shaped 

 structure within the contour of the nose-groove (see fig. 6). 

 In the posterior portions of the vertical fins we can now 

 see true rays, 4 or 5 in the dorsal fin, and 3 or 4 in 

 the anal fin. 



Specimen no. 5 is 58 mm long, having 108 preanal 

 and 49 postanal segments, 157 in all. In this larva we 

 find no indication of separated nostrils, but there are more 

 numerous and more fully developed rays in the vertical 

 fins, 7 or 8 in the dorsal fin, and 6 in the anal fin. The 

 caudal fin has 16 rays, H x bearing seven, and H 2 nine. 



Specimen no. 6 has a length of 59 mm, and has 

 106 preanal and 46 postanal segments, 152 in all. It 

 agrees in all essential points with no. 5; the caudal fin, 

 however, has 16 rays, H 1 and H 2 having eight each, and 

 we find more indications of interspinous elements in the 

 vertical fins. 



Head of larva no 



attains its greatest height just in front of the anal aperture, 

 which is placed far backward, for we find 97 preanal and 

 48 postanal myomeres, 145 in all. The head of this larva 

 is represented on fig. 7. 



Specimen no. 8 is 107 mm long, with a maximum 

 height of 9 mm, and has 106 preanal and 49 postanal 

 myomeres, 155 in all. The dentition is complete, and 

 the rays of all the fins are developed, the caudal fin having 

 17 (H j nine and H 2 eight). 



Specimen no. 9 appears to be undergoing metamor- 

 phosis. It is 107 mm long, with a maximum height of 

 10 mm. All the fins are provided with strong rays, U 1 

 of the caudal fin having eight, H 2 nine rays. 



Metamorphosis shows itself thus: the anus is placed 

 farther forward than in the previous specimens, there being 

 only 82 preanal, but 70 postanal segments, 152 in all. 

 The snout has a rather rounded profile, and protrudes 

 far beyond the point of the lower jaw, whereas it is quite 

 pointed and protrudes slightly in the previous individuals. 

 Teeth are entirely wanting. Further, the anterior nostril 

 has become very distinctly tubular, and projects from the 

 contour of the head when looked at from above. That the 

 metamorphosis is not very far advanced appears, however, 

 from its great height, its compressed body-form, and because 

 the anus is still placed far back. 



Specimen no. 10 is at the same developmental stage 

 as no. 9. It is 112 mm long, with a maximum height 



