THE SHOULDER-GIRDLE IN FISHES. 9 



B. No splint-bones ; supra-scapulse as small tubercles, half-segmented from the scapulae. 

 Example. Squatina angelas, Dumeril. 



In the ' Osteological Catalogue of the Hunterian Museum ' (Roy. Coll. Surg.) the reader 

 will find no mention of an entire skeleton of the Monk-fish, but there has been a perfect one 

 (prepared by the author of this Monograph) added to the Museum since the publication of that 

 Catalogue. 



This preparation shows how massive the Shoulder-girdle is in this connecting link between 

 the Skate and the Shark on the whole it agrees most with the former ; but the supra-scapula is 

 a mere semi-detached knob, which is articulated loosely with the spine ; and there is only one 

 fenestra in the base of the scapula, and running a little, perhaps, into the head of the coracoid. 

 I shall call this simply the " scapular fenestra," as it is evidently the counterpart of the supero- 

 posterior fenestra of the Skate (Plate I, fig. 2, sc. f.). We shall see it again in Class after Class 

 as we ascend the scale. The scapula of Kfjuatina is not high, but it becomes very broad where 

 it passes into the massive coracoid ; this latter part turns inwards at less than a right angle, and 

 the transverse, or epicoracoid part, by union with its fellow of the opposite side, forms a strong 

 subthoracic beam, in which there is no sign of the original division, either by thinning down of 

 the bar, or by arrest of the dense pavement of polygonal bone-grains. 



c. No splint-bones ; supra-scapulae as long styloid bars, only distinguished from the scapulas 

 by an arrest of the bony pavement, over the tract where segmentation should have taken place. 



Example. Galeus vulyaris, Cuv. 



The skeleton of the Tope, or smooth Dog-fish, in the Hunterian Collection (' Osteol. Catal.,' 

 vol. i, p. 92, No. 397), is somewhat the worse for its age, but there is a fresher skeleton (made 

 by the writer) which has been added since the printing of the Catalogue (1853). In that spe - 

 cimen the Shoulder-girdle of Galeus may be studied. There is a figure in Huxley and Hawkins's 

 'Atlas' (1864, plate 11, fig. 10), of the Shoulder-girdle of this species; it is a side view, and 

 shows the upper part well ; but the epicoracoid is foreshortened, and its union with its fellow is 

 not represented. Moreover, the wrinkled condition of this, as of all dry skeletons of the 

 Plagiostomes has obscured the view of the " scapular fenestra." This passage may be found, 

 however, even in the dry preparation ; the shaded fossa in Mr. Hawkins's figure, close behind 

 and above the letter a, represents a valley which leads to it ; it is small, oval, and nearly vertical, 

 and divides the base of the scapula into a scapula proper and a prae-scapula, as in the Monk-fish 

 and the Anourous Batrachia (see Plate V, fig. 15, sc. f.). 



Mr. Hawkins's figure well shows the relation of the pointed supra-scapular " horns " to the 

 scapula, and the obliquely transverse band of unencrusted cartilage which separates the two 

 regions ; a similar band, but smaller, marks the boundary-line between the scapula and coracoid. 



The epicoracoids of Galeus thin-out considerably ; they are very thin where they unite, and 

 bend on each other in the dry preparation ; moreover, there is no bony crust on their edges, the 

 whole of the cartilage continuing soft for a few lines outwards. 

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