of the, Fishery Board for Scotland. 273 



extremity of the second basibranchial. This bone lias a wing-like 

 expansion to either side, and on the hind part of the same there'' is a 

 small toothed area. The presence of the teeth on the second basi- 

 branchial serves to distinguish this bone from that of the cod and 

 saithe, in which there are no basibranchial teeth. The bone narrows 

 immediately behind the toothed area and ends in a slender extremity, 

 which IS hollowed out for a ligament which attaches it to the cartilage 

 mass which is situated between the hypobranchials and the bases of the 

 fourth ceratobranchials, and which is continued posteriorly to the lower 

 pharyngeals. The lower extremities of the first and" second hypo- 

 branchials are received in depressions in the side of the cartilaginous body 

 uniting the first and second basibranchiais. The third basibranchial is a 

 long slender splinter-bone joining the upper surfaces of the first and 

 second bones, and lying directly on the top of the cartilage. It fits into 

 a suture in either bone. Its long hind pointed extremity fits into a long 

 hollow 111 the second basibranchial, and reaches back as far as the toothed 

 areas. 



Hypohranchials (hp. Br.). 

 Ltthe, Fig. 21, PI. ly. 



There are three hypobranchials on either side. The first two articu- 

 late below with the basibranchial cartilage and above with the first and 

 second ceratobranchials respectively. The third hypobranchial is bound 

 to the hind part of the second basibranchial, and its anterior slender 

 extremity passes downwards under the second hyoobrauchial. The third 

 hypobranchial has a broad i)osterior edge, and to the outer portion of it 

 are attached the third ceratobranchials, while to the inner part are 

 attached by cartilage the fourth ceratobranchials. 



The first two hypobranchials resemble one another and are very 

 difi-erent from the third. The second is shorter than the first. If 

 they are viewed from above, the first and second bones are seen to be 

 bent, with the lu-curvature on the side next the basibranchiais. The 

 bend does not take place at the middle of the length of the bone • the 

 lower arm is the shorter. On the first hypobranchial there is a lateral 

 expansion on the outer side at the knee ; it runs along the Ion" arm for 

 some distance. In the second there is only a small process on°the outer 

 side of the corner. 



The third hypobranchial resembles much in shape a trowel ; when in 

 ^tu, the trowel is upside down, with its handle projecting downward and 

 forward under the second hypobranchial. The end of the handle is 

 liollow, and serves for the attachment of a ligament. 



Ceratobranchials (cer. Br.). 



Lythb, Fig. 21, PI. IV. 



Of the ceratobranchials the greatest difficulty arises in distinguishing 

 the second and third. The first is rather longer than the other three 

 which are of about equal length. The ceratobranchial is a loner curved 

 bone, roughly triangular in section, and having a longer or shorter 

 groove, in which are lodged the blood vessels and the bases of th.^ crjU 

 filaments. Tlie inferior ends of the bones are of rather greater thickiress 

 than the upper extremities. The second and third alone have complete 

 grooves running the whole length of the bone. In the first there is a 



s 



