38 SHOULDER-GIRDLE AND BREAST-BONE. 



glass, would, by spreading into a fan above, and developing the inturned wings below, ultimately 

 come to assume the form here figured and described. 



There are five brachial rays, four of which apply their lunate bases to the crenate 

 " glenoid " margin of the Shoulder-blade ; it is the uppermost but one which has aborted the 

 scapula. The uppermost ray is much the smallest ; it is pointed in front (fig. 4 C, b. 1), and 

 actually bends round to apply itself to the front of the starved scapular cartilage. The four 

 larger rays are flattened hour-glasses ; they have soft ends, and lanceolate interspaces ; and they 

 are perfectly cloven from each other. The elegant interspaces are lessened by transverse periosteal, 

 spicular growths, especially proximally ; the free edge of the upper and of the lower ray is ren- 

 dered jagged by similar growths. A comparison of. the Shoulder-girdles of Ostracion and Tetrodon 

 will show how widely apart these two types of Plectognaths lie. 



Example 3. Triacanthus - ?, sp. 



The family Balistidse brings us much nearer to the typical Acanthopterous Fishes, and I 

 shall merely give the general characters of the Shoulder-girdle in this group. My observations 

 have not been made from fresh dissections, but from some excellent skeletons in the Hunterian 

 and British Museums. In the former there is one of an unnamed species of Batistes (' Osteol. 

 Catal.,' vol. i, p. 76, No. 326), and aUsootS./orcipahu, Will. (No. 327) ; in the latter there is 

 a preparation of a Triacanthus, another of Batistes aculeatus, Linn., from the Mauritius, and two 

 others of the genus Batistes, the species not known. These skeletons show stronger bone than 

 is seen in Tetrodon, and there is a great approach to the skeleton of the Dory (Zeus] ; the bones 

 are, however, feebler and more fibrous than in that type. A description of the Shoulder- 

 bones of Triacanthus will serve for the rest. 



The " post-temporal " is flat, and closely adherent to the occipito-temporal region, as in 

 Zeus, Tetrodon, Lophius, &c. The " supra-clavicle " is rather small and styloid ; the clavicle 

 is quite normal, and not unlike that of high-bodied Fishes generally; the "post- clavicle" agrees, 

 not with that of the Tetrodon, but with that of the Dory (Plate I, fig. 14, p. cl.). It nearly 

 meets its fellow below at a great distance from the clavicle; it is strong, straightish, and is 

 expanded above, where it is tied to the inside of the clavicle. The Shoulder- plate itself is 

 relatively large, and there are only two ossifications in the adult Fish ; these are the " scapula " 

 and the " coracoid." The former of these is fenestrate, and is thus partly divided into a " prae- 

 scapula " and " scapula proper," as in nearly all truly typical Fishes. The latter the " coracoid " 

 has a broad subquadrate " prae-coracoidal " portion obscurely marked off from the long, large- 

 winged "coracoid proper;" the anterior wing is the broadest. The coracoids end near the 

 abdominal line, like the clavicles and post-clavicles. 



