EINAR LEA 



[REP. OF THE "MICHAEL SARS" NORTH 



In the following brief descriptions, the principal stress 

 has been laid on the number of segments, which must 

 be considered the chief character in comparing leptoce- 

 phalids among themselves, and in referring leptocephalids 

 to their parent forms. This single character, however, 

 does not always suffice either one way or the other, for 

 we find that different species of eel have about the same 

 number of segments (vertebrae), and that the number of 

 segments in different individuals of the same species may 

 vary, so that sometimes it is impossible to determine a 

 species, or to refer a larva to its parent form on the 

 basis of the number of segments alone. I have therefore 

 found it necessary to include other characters, such as 

 the number of rays in caudal fin, in some cases also the 

 number of rays (interspinous elements) in the vertical 

 fins, etc. On the other hand the measurements of the 

 proportions of the body may not be diagnostically important, 

 although occasionally we can make use of them in order to 

 compare larvae of the same species in different 

 developmental stages. These measurements have 



been made for the purpose of studying the variations in 

 the development of the larvae. In some cases it has been 

 possible to study some features of this developmental 

 variation, where the material included different stages of 

 development or other developmental stages than those 

 previously described. 



The descriptions will thus make it possible 1) to 

 distinguish the different species of larvae from one an- 

 other (number of segments, etc.), 2) to distinguish between 

 the different stages of development of the same species 

 (dimensions of body, development of nostrils and fin- 

 rays, number of teeth, etc.), and 3) to refer the larvae 

 to their parent forms (number of segments and fin-rays, 

 etc.). 



At present the last-mentioned determination is pos- 

 sible only in a few cases, one reason being that the 

 number of vertebrae in many of the adult forms is un- 

 known. I have found accounts of the number of verte- 

 brae in the following species: 



found. 



Muraenoids whose segments are counted. 



The numbers given are the lowest and highest found, and reference is made to those authorities, were these extreme values are 

 Species, which are not found in the Atlantic, are distinguished by asterisks. 





Number 







Number 





Name 



of 

 segments 



Authority 



Name 



of 

 segments 



Authority 



I. Species, the larva! forms of 

 which are known. 







Conger vulgaris Cuv 



153—164 



SMITT (32) 



Day (7) 







larva: L. stenops (in part), 





Cyerna atrum Gunther 



73 

 75—77 



Autor 



Morrisii, punctatus .... 



156-159 

 208 



Autor 



Bellotti (3) 



larva: L. CyematLs atri 



Anguilla chrysypa (rostrata) Raf. . . . 



larva: L. GrassL Eigenmann 



and Kennedy 



103—113 

 105—108 



Petersen (23) 

 Eig. a. Kenn. (9) 



larva : 



> 200 

 240—249 



Schmidt (30) 

 Supino (34) 

 Bellotti (3), 



Autor 





Anguilla vulgaris Turt 



111 — 119 



Schmidt (24) 

 Petersen (23) 

 Schmidt (24) 









Gastrostomus Bairdii Gill a. Ryder 



110 



Zugmayer (37) 



larva : L. brevirostris Kaup .... 



111—119 



larva: L. Gastrostomi Bairdii. 



> 108 



Autor 







Autor 









Congromuraena balearica de la Roche 



about 130 



Schmidt (28) 



11. Species, whose larval stages 







larva: L. taenia, inornatus, 







are not yet identified. 







diaphanus 



123-137 



Autor 



Muraenesox coniceps Jord. a. Gilb. 



111 



Jord a. Dav. (21) 







133 



Supino (33) 





116 



Gunther (19) 





131—136 



Schmidt (29) 



Gymnothorax meleagris Shaw 



nebutosus Bl 



120 



— (19) 



Congromuraena mystax de la Roche 



about 138 



- (28) 



122 



(19) 



larva: L. Haeckeli, Yarrelli, 













Bibroni, Gegenbauri, 

 Kdllikeri, stenops (in 







* — nebulosa „ 











* — sea bra „ 



123 



Garman (12) 



132-147 



Autor 



Moringua raitaborua Ham 



126 



(12) 





139-143 



Grassi (16) 



Gymnothorax undulatus Lacep 



126 



(12) 



larva: 



140—143 

 146-151 



- (16) 

 Schmidt (26) 



Histiobranchus infernalis Gill 



llyophis Brunneus Gilb 



130 

 127—132 



Gunther (19) 

 (19) 



Synaphobranchus pinnatus Gronov. 





larva: L. Synaphobranchi pin- 







Ophichthys ocellatus Les 



132 



Autor 





. 144—157 



Autor 





132 



— 



