I. Introduction. 



During the "Michael Sars" deep-sea expedition in described where the number of muscle-seg- 



1910 some specimens of leptocephalids (larval muraenoids) ments is stated. 



were caught. They belong to rather many different species The name Leptocephalus, which according to the 



(26 in all) and it proved difficult to decide, which of them rules of priority should be applied to the genus Conger, 



are new to science because so many descriptions of lep- has in this paper been employed as a sort of provisional 



tocephalids are imperfect in omitting to state the number name for muraenoid larvae, as it is used for instance by 



of muscle-segments. Prior to Grassi's and Calandruccio's Dr. Johs. Schmidt. Those larvae whose parent forms are 



epoch-making investigations in regard to the larvae of known have been given the names of the adults (like L. 



eels and their metamorphosis, the descriptions of lepto- Congri vulgaris). 



cephalids were mainly based upon various dimensions of As supplementing the short descriptions we give repro- 



the body, dentition etc., but as these characters are sub- ductions of photographs and drawings, taken shortly after 



ject to great variation, they will not suffice for the deter- the "Michael Sars" returned from the Atlantic, 



mination of species. We find an empiric proof of this in Formaldehyde (4 °/o) was used as a preserving fluid 



Grassi's table in regard to the connection between larval during the cruise, but as some of the larvae had become 



and adult muraenoids. swollen and damaged they were transferred to a fluid 



It is evident from this table 1 ) that larvae of the very composed of 3 parts of alcohol (96 °/o), 3 parts of for- 

 same adult form have been described under as many as maldehyde (3 %), and 2 parts of glycerine, in which 

 six different names due to the fact that height of body, most of the larvae have kept very well. 

 situation of anus, presence or absence of fin-rays, etc., As for the literature consulted, little attention has 

 have been regarded as specific characters. C.H.Eioenmann been paid to works, in which the species are mentioned 

 and C. H. Kennedy (9) have in consequence erred in without giving the number of segments, many of them 

 describing as Leptocephalus Congri vulgaris a form which especially in Italian are difficult to obtain, and I have 

 evidently does not belong to this well-known species, had to content myself with what I could find in the 

 Similarly Stromman (33) has described a new form which, libraries of Bergen and Christiania. Those wishing fur- 

 according to Dr. Johs. Schmidt (29) who has examined ther information, may be referred to the following:- 

 Stromman's type specimen, is identical with the larva of J. V. Carus: Ueber die Leptocephaliden. Leipzig 1861 

 Congroniuraena balearica. The larva of this eel had pre- (for older literature). 



viously- been described under the name of L. taenia, L. P. H. Stromman: Leptocephalids in the University Zoolo- 



inornatus and L. diaphanus. gical Museum at Upsala. Upsala 1896. 



Guided by such considerations I have deemed it Johs. Schmidt: Contributions to the Life-History of the 



justifiable to adopt the following principle in naming the Eel (Anguilla vulgaris, Flem.). Rapports et Proces- 



species here described: a species is regarded as verbaux du Conseil Permanent International pour l'Explo- 



new when it differs from all species formerly ration de la Mer. Vol. V. Copenhagen 1906. 



') Leptocephalus stenops (Bellotti) in pait, also L. morrisi and L. punctatus Conger vulgaris 



hwckeli, yarrelli, bibroni, gegenbauri, kollikeri, stenops (in part) Congromurwna mystax 



taenia, inornatus, diaphanus Congromurcena balearicus 



kefersteini Ophichlhys sp. divers. 



longirostris. Hyoprorus messinensis Nettastoma melanurum 



oxyrhynchus etc Saurenchelys cancrivora 



sp. nov Murcena helena 



