ICHTHYOLOGICAL COLLECTIONS OF THE ALBATROSS. 403 
Family DALLIIDA. 
27. Dallia pectoralis Bean. Alaska Blackfish. 
- The blackfish is abundant along the Nushagak River, and 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 Xenomi, 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 
- eranium 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 
_normaland usual. It is evident that this character is not of high taxonomic value, 
and would not of itself warrant any very wide separation of 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, usually exhibiting very distinct division into upper 
and lower halves, which may be taken to represent the hypo- and hyper-coracoid 
élements. 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 Notacanthus 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. 
as 
i 
Family SYNAPHOBRANCHIDZ. 
28. Histiobranchus bathybius (Giinther). 
A specimen 575 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 255 mm., the length of the head 
_ 59 mm., and length of pectoral fin 17mm. The vomerine teeth are in an irregular, 
_ rather narrow band, reaching posteriorly to opposite hinder margin of orbit. 
