FISHES OF HAWAIIAN ISLANDS. 
75 
a. Insertion of dorsal behind middle of pectoral. 
b. Gape of mouth scarcely reaching orbit Promyllantor, p. 75 
bb. Gape of mouth reaching at least to below middle of eye Leptocephalus, p. 75 
aa. Insertion of dorsal before middle of pectoral. 
c. Teeth present on jaws and vomer Congrellus, p. -76 
cc. No teeth on jaws or vomer Veternio, p. 78 
Genus 42. PROMYLLANTOR Alcock. 
Body stout, with the muscular and osseous systems well developed, and the tail about as long 
as the trunk; eye rather small, cleft of mouth narrow, not extending behind middle of eye; villiform 
teeth, in broad bands in jaws, and in a broad, confluent patch on palate; nostrils lateral; tongue 
free; gill-openings widely separate; 4 gills with wide clefts; no scales; muciferous cavities of head 
well developed; the dorsal begins some distance behind the occiput; pectoral and vertical fins well 
developed, the latter confluent. Allied to Congermurxna. (Alcock). This genus differs from Lepto- 
cephalus in the dentition and in the posterior position of the nostrils. Deep-sea fishes of the Arabian 
seas and about the Hawaiian Islands. 
The single Hawaiian species (P. alcocki) is fully described in Section II. 
Promyllantor Alcock, Ann. Mag. Nat. Hist., October, 1890, 6th series, No. 6, 310 ( purpureus ). 
Genus 43. LEPTOCEPHALUS Scopoli. The Conger Eels. 
Body formed as in Anguilla; the skin scaleless; head depressed above, anteriorly pointed; lateral 
line present; mouth wide, its cleft extending at least to below middle of eye; teeth in outer series in 
each jaw equal and close-set, forming a cutting edge; no canines; band of vomerine teeth short; 
tongue anteriorly free; vertical fins well developed, confluent around tail; pectoral fins well developed; 
dorsal beginning close behind pectorals; gill-openings rather large, low; eyes well developed; posterior 
nostril near eye; anterior near tip of snout, with a short tube; lower jaw not projecting; skeleton 
differing in numerous respects from that of Anguilla; vertebrae about 56 -f- 100. In most warm seas. 
This genus contains the well known and widely distributed conger eel and 3 or 4 closely related 
species. The earliest generic name used for members of the group is Leptocephalus, based on a curious, 
elongate, transparent, band-like creature with minute head and very small mouth, found in the waters 
of Europe, and known as Leptocephalus morrissi. This has been shown by Gill, Gunther and Facciola 
to be the young and larval form of Leptocephalus conger. A number of genera and species of the sup- 
posed family of Leptocephalidx have been described, but there is no doubt that all of them are larvae, 
some of eels, as Conger, Congermurxna, Oxystomus, and Nettastoma, others of isospondylous fishes, as 
Albula, Elops, Alepocephalus, Stomias, etc. (Gunther, Cat., VIII, 136.) It is thought by Dr. Gunther 
that the leptocephalid forms are probably “individuals arrested in the development at a very 
early period of their life, yet continuing to grow to a certain size, without corresponding develop- 
ment of their internal organs, and perishing without having attained the characters of the perfect 
animal.” The recent observations of Dr. Gilbert on the larvae of Albula, Elops, and Conger, however, 
seem to point to the conclusion that these curious forms are normal young, and that the individuals 
grow smaller in size for a time with increased age, owing to the increasing compactness of the tissues. 
Inasmuch as the name Leptocephalus has been associated for more than a century with larval forms, 
it is a decided inconvenience to accord to it precedence as a generic name over Conger. The strict law 
of priority, however, demands its retention, and the tendency among systematic zoologists is to 
recognize as few exceptions as may be to this rule. The unfamiliar names Oxyurus and Helmictis are 
both earlier than Conger. 
(a) Larval forms. 
Leptocephalus Scopoli, Int. Hist. Nat., 1777, 453 (morrissi). 
Oxyurus Rafinesque, Caratteri, 19, 1810 (vermiformis) . 
Helmictis Rafinesque, Indice d’lttiologia Siciliana, 62, 1810 ( punctatus ). 
Helmichthys Costa, Fauna Napoli, Pesca, 1854 (diaphanus) . 
? Leptocephalichthys Bleeker, Act. Soc. Sci. Ind. Nederl., I, Manado, 69, June, 1856 (hypselosoma) . 
? Diaphanichthys Peters, Monatsber. Ak. Wiss. Berl. 1864, 339 ( brevicaudus ). 
