48 ZOOLOGY. 
BDELLOSTOMA POLYTREMA, Girard. 
Pirate XXXIII, Figs. 1—5. 
Spec, cHar. Fourteen respiratory apertures and gills on either side. Twelve teeth on either 
side in the posterior as well as in the anterior row. Eyes present. Color not preserved in the 
specimen described. 
Syn. Bdellostoma polytrema, Grp. Proc. Acad. Nat. Sc. Philad. VIT, 1854, 199. 
Ors. In the second part of his memoir on the ‘‘Comparative Anatomy of the Myxinoids,”’ 
Prof. Miiller is inclined to believe that all the species enumerated in the first part, and which 
came to his knowledge, are but simple varieties of Bdellostoma forsteri (Petromyzon cirrhatus of 
Forster), an inhabitant of Queen Charlotte’s bay, New-Zealand. This would give a remark- 
able geographic range to that species, as it is well known that Bd. heaatrema and Bd. hetero- 
trema, both, inhabit the Cape of Good Hope; Bd. dombeyi the coast of Chile, and Bd. heptatrema 
the southern seas. The latter is more closely allied to Bd. forsteri than any other, and its 
locality in the southern seas may after all prove not to be far from New-Zealand. 
Since Bd. polytrema has come to light, bearing in itself the remarkable fact of having fourteen 
pairs of gills, instead of six and seven, which are the usual number in the species previously 
known, we deem it advisable to retain them all as provisionally distinct. Moreover, the genus 
would not be limited to the austral hemisphere, for we find mentioned, in the ‘‘ Fauna Japon- 
ica,’’ p. 310, a species under the name of Heptatrema cirrhatum, which is another Bdellostoma 
(Bd. burgeri), judging of it by the figure given on Plate cxim, which exhibits a similar . 
aspect of the head, the same shape of the mouth and cephalic tentacles. The eyes appear to be 
very small, A singular circumstance is mentioned by Mr. Biirger, by whom it was collected, 
and who states that during the summer months these fishes, generally a foot and some inches 
long, are caught in great numbers on muddy bottoms in the Bay of Simabara, at some dis- 
tance from Nagasaki, and that the Japanese usually eat them raw. This latter species is more 
slender than the one of which we give a figure and a description. 
Descr. Bdellostoma polytrema is about fifteen and a half inches long. The body is subcylin- 
drical anteriorly and compressed posteriorly, particularly upon the tail, which constitutes a 
little less than one sixth of the entire length. The head is slightly tapering towards the snout. 
The nasal opening (a) which terminates its anterior extremity, is transversally elliptical and 
very large, provided on each side with two tentacles; the uppermost (0) is the smallest and 
directed upwards; the other, (c), a little longer, stretches laterally outwards. Underneath the 
head we find the mouth (d), longitudinally subovoid, beset with minute cirrhi around its 
external margin. A broad and flattened tentacle (/), directed inwardly, may be seen extending 
over the buccal aperture across the middle of its longitudinal diameter. Another slender and 
second pair of buccal tentacles (e) is inserted near the base and external margin of the latter 
flattened pair, stretching outwardly backwards. 
The tongue (fig. 5) is subcordiform, bearing two arched series of subconical teeth obliquely 
directed backwards. The posterior series is composed of considerably smaller teeth than the 
anterior one. In both there are twelve teeth on either side. A tooth from each series is rep- 
resented isolated (a) on the right side of figure 5. To the left (6) may be seen the hook-like 
palatine tooth, subconical in shape, and likewise directed backwards. 
The eyes are not very conspicuous, and are situated at about eight tenths of an inch from the 
extremity of the snout. A series of mucous pores may be seen extending below the middle of 
the sides, from near the anterior part of the body to near the extremity of the tail. The six 
or seven anterior holes are much larger than the remaining ones, which diminish backwards, 
becoming almost minute along the caudal region. The respiratory apertures are situated im- 
mediately above the series just alluded to, and may easily be distinguished by their larger size. 
