252 ZOOLOGY. 



BDELLOSTOMA POLYTEEMA, Girard. 



Plate 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 iireserved in the 

 specimen described. 



Syn. BiMlostomaimhjfrema, Gkd. Proc. Acad. Nat. Sc. Philad; VII, 1854, 199. 



Obs. 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 hut simple varieties oi BdeUostoma forsteri (Petromywn cirrJiatus 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 Sd. hexatrema and Bd. hetero- 

 trcma, both, inhabit the Cape of Good Hope ; Bd. domhei/i the coast of Chile, and Bd. hejytatrema 

 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, beai-ing 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 imder the name of Heptatrema cirrhatum, which is another BdeUostoma 

 {Bd. hurgeri), judging of it by the figure given on Plate cxliii, 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.. Burger, 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 Jajjanese usually eat them raw. This latter species is more 

 slender than the one of which we give a figure and a description. 



Desck. BdeUostoma 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 (6) is the smallest and 

 directed upwards; the other, (c), a little longer, stretches laterally outwards. Underneath the 

 head we find the mouth {d), longitudinally suhovoid^ 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 ponsiderably 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 regioci. The respiratory apertures are situated im- 

 mediately above the series just alluded to^ and may easily be distinguished by their larger size. 



