THE SHOULDER-GIRDLE IN FISHES. 45 



Fam. 



Example 1 . Ambit/opus ? 



My specimen of this tropical Gobioid Fish * measures 20 inches in length ; the Woodcut 

 (fig. 6 A) shows its Shoulder-bones of the left side and part of the right ; magnified two diameters. 



The post-temporal (p. t.) has a small, flat body, with a hinge below for the splint beneath it ; 

 and two long forks. The supra-clavicle (s. cl.) has the normal spatulate form, with the oblique 

 condyle above for the supra-temporal ; it overlaps by its flat lower end the forked top of the 

 clavicle. The clavicle (cl.) has two flat spines at the top, the front one reaching furthest upwards ; 

 it is a large, sinuous, ridgy bone, bent suddenly below the upper third, and presenting a narrow 

 but deeply grooved front towards the gill-opening. Behind, it sends an upper posterior plate, 

 which lies in front of and slightly external to the prae-coracoid (p. cr.) and middle brachials (b.). 

 More than the upper half of the lower third gives off an ear-shaped "inter-clavicular process," (i. cl.p.) 

 in front of which is seen the body of the coracoid (cr.). The clavicle widens below, is subangular, 

 convexo-concave on the outside, and scooped within to receive the epicoracoid cartilage (e. cr.). 

 The post-clavicle (p. cl.) is a slender, but strong style ; it is attached within the head of the clavicle ; 

 and is considerably smaller than that of Coitus (Plate II, fig. 12, p. cl.). As in Cottus, the Shoulder- 

 girdle moiety is segmented into three parts, all wide apart ; the first cleft being dependent upon 

 the excessive growth of the middle brachials (b.); and the latter caused by the intrusion of the large 

 clavicle. The scapula (sc.) is a very small bone; it is a low triangle, with the base attached to 

 the clavicle, and the upper angle notched ; it causes an emargination of the glenoid edge of the 

 uppermost brachial (b. 1), with which it is strongly clamped by means of periosteal layers, but 

 from which it is persistently separate. A space more than the length of the scapula intervenes 

 before we reach the pointed, unossified upper end of the prae-coracoid (p. cr.). This part is 

 nearly in a line with the body of the coracoid (cr.), which is flat, but stout, and forms one bone 

 with the base of the prae-coracoid. The lower end of the coracoid is soft; it is angular in shape 

 and lies in the angle between the body of the clavicle and its "inter-clavicular process " on its 

 outside. The distal coracoid element the epicoracoid (e. cr.) is about the same distance from 

 the end of the coracoid that the pree-coracoid is from the scapula ; it is an oval, double plate of 

 hyaline cartilage, and lines the smoothly scooped fossa, inside the distal end of the clavicle ; so 

 that the clavicle, in the adult, passes obliquely from the inside to the outside of the Shoulder- 

 girdle elements, and it is very probable that the inter-clavicular process is a later growth 

 than the body of the clavicle. As for the upper part of the clavicle, it simply lies in front of 

 the scapula and coracoid. 



The brachial rays (b. 1 4) are extremely large, very flat, and together form a semi-oval 

 plate, the rounded edge being crenate, and the anterior edge straight, and applied to the 

 shoulder-bones. This is not quite a straight margin, for it is notched above for the scapula ; it 

 bulges in the middle, where it reaches the clavicle, and has the lower third, which is applied 

 to the prae-coracoid, straight. There is no actual division of the soft cartilage in front ; behind, 



1 The gift of Mr. Waterliouse Hawkins. 



