ICHTHYOLOGICAL COLLECTIONS OF THE ALBATROSS. 403 



Family DALLIIDiE. 



27. Dallia pectoralis Beiiu. Alaska Blackfish. 



The blackfish is abuiuhiut aloug the Nushagak River, aud there as elsewhere it is 

 an important source of food to the natives. Specimens were presented to us by Mr. 

 Clark, proprietor of the station at Nushagak. The characters assigned by Dr. Gill 

 to his order XeH07ni, of which Dallia is the sole representative, seem to need some 

 modifications. The group is thus defined by him: 



"Teleosts with the scapular arch free from the cranium laterally and only abutting 

 on it behind, coracoids represented by a simple cartilaginous plate without devel- 

 oped actinosts, and with the intermaxillary and supramaxillary bones coalescent." 



The last of these three characters we have not been able to verify, as the premax- 

 illa, while lying closely appressed to the maxilla, is readily separated from it, the 

 two being in no sense "coalescent." The expression "scapular arch free from the 

 cranium laterally" refers to the simple nature of the post-temporal, which is attached 

 as usual to the epiotic, but seems at first sight to lack entirely the inner fork to join 

 the parotic process of the cranium. Closer examination shows, however, that a 

 strong ligament replaces the lacking arm, and answers to it in all its relations. We 

 find, furthermore, that while in some specimens it retains its ligamentous condition 

 the entire distance between the opisthotic and the simple post-temporal, in others the 

 proximal portion of the ligament is more or less ossified, the bony rod thus formed 

 being an integral part of the post-temporal and representing the proximal portion 

 of the missing fork. As stated, this ossification invades the ligament to a varying 

 extent in different specimens. In at least two which have come under our observa- 

 tion, the fork of the post-temporal thus formed has extended almost the entire dis- 

 tance across to the opisthotic, the shape and relations of the bone being then entirely 

 normal and usual. It is evident that this character is not of high taxonomic value, 

 and would not of itself warrant any very wide separation o{ Dallia from what were 

 at first considered to be its nearest relatives. 



The case is different, however, when we come to examine the coracoid portion of 

 the shoulder girdle. As stated by Dr. Gill, we deal here with a cartilaginous plate 

 in which no ossifications occur, and which is followed immediately by the fin rays, 

 without the intervention of actinosts. This coracoid cartilage is an extremely thin 

 and delicate imperforate lamina, usuaDy exhibiting very distinct division into upper 

 and lower halves, which may be taken to represent the hypo- and hyper-coracoid 

 elements. In its distal third the plate begins to break up, by longitudinal sub- 

 division, into a fringe of narrow cartilaginous strips. These approximately equal 

 in number the pectoral rays, and join the latter directly, the basal portion of each 

 pectoral ray forking slightly to receive the tip of the cartilaginous strip. 



In the deep-sea spiny eels of the genus Notacantlms there is a somewhat similar 

 condition of the coracoid elements, inasmuch as the hypo- and the hyper-coracoid 

 though present, are merely shell-like rudiments surrounded by cartilage, and the 

 actinosts are greatly reduced. It seems probable that we are dealing in the two 

 cases with independent degenerations of the shoulder girdle, and that the two groups 

 are not really related. 



Family SYNAPHOBRANCHIDiB. 



28. Histiobranchus bathybius (Giinther). 



A specimen 57.^ mm. long, from station 3308 in Bering Sea, depth 1,625 fathoms. 

 The color is light brown, darker on head and belly, and on the fins. The depth at 

 vent is 42 mm., the distance of vent from snout 2,55 mm., the length of the head 

 59 mm., and length of pectoral fin 17 mm. The vomerine teeth are in an irregular, 

 rather narrow band, reaching posteriorly to opposite hinder margin of orbit. 



