44 SHOULDER-GIRDLE AND BREAST-BONE. 



But there is another segment into which the Shoulder-girdle moiety is divided, viz. the 

 epicoracoid; this is not shown in fig. 12 of Plate II, but is shown in the Woodcut (fig. 5 C, e. cr.) 

 in Cottus scorpius, Bl. I have already described this part in the Lepidosiren, where it is largely 

 developed, but I only lately came across this part in the Teleostei. The Shoulder-girdle moiety 

 in these Cottoids, and in other Fishes with huge pectoral fins, is subject to a remarkable form of 

 segmentation ; first, the large brachials grow through the glenoid part, dividing the scapula from 

 the prae-coracoid, and then the clavicle passes between the foot of the coracoid and the epicora- 

 coidal mass. The splint-bones ossify at a very early stage of the embryonic Fish ; and, 

 undoubtedly, whilst the cartilage is in a very soft condition, before the deposit of the inter-cellular 

 substance. The Woodcut (fig. 5 C) shows a section of the lower part of the two clavicles (cl.) 

 and in that acutangular space is seen the epicoracoid mass (e. cr.) which belongs to both sides of 

 the body, although the divisional line cannot be seen in this case ; it can be seen, however, in 

 Gobius niger. This breaking-up of the coraco-scapular plate in the Fish Class is curious enough, 

 and is not seen in the air-breathing, cold-blooded Ovipara. 



The four brachials of Cottus bubalis (Plate II, fig. 12, b. 1 4) are large, squarish, flat, 

 smooth bones, and are highly ossified ; the lowest but one is the largest. There are three small, 

 vertically oval fenestrae, the uppermost of which lies between the small, irregular, upper brachial 

 and the scapula. Altogether, the skeleton of Cottus bubalis is most intensely ossified, and the 

 Shoulder-girdle and arm partake in this strong calcification ; but the morphological characters in 

 my region of this Fish are interesting in the highest degree, and a thorough knowledge of 

 them is no mean help towards a true appreciation of the homologous parts in the entire Class. 



Example 2. Agonm cataphractus, Linn. 



The Armed Bull-head, or Pogge, is a curious isomorph of the Hippocampus, and may be 

 said to lie somewhat between the Cottoids and the Lophobranchii, although agreeing much more 

 with the former than with the latter. 



The ganoid armour of this Fish is combined with a weaker skeleton than that of Cottus 

 bubalis. The clavicle of Agonm is much broader than that of Cottus, and the outer part of the 

 large anterior plate is directed backwards, instead of forwards as in Cottus ; the posterior plate is 

 less developed, and I fail to find the smaller inter-clavicle. The post-clavicle is a feebler style. 

 The scapula has a large, obliquely oval " fenestra," and it is continuous with the prae-coracoid 

 below, there being a "glenoid," band of cartilage uniting the two regions. 1 The coracoid and 

 prse- coracoid are very similar to those of Cottus ; but the whole piece is less strongly ossified. 

 The epicoracoid is larger than in Cottus scorpius, and it was in this species that I first saw a 

 Teleostean repetition of what I had until then only seen in the Lepidosiren. 



The brachials are still relatively larger than in Coitus, but there are only three ; the middle 

 bone is the largest, for it is the uppermost bone which is aborted. These bones have a con- 

 siderable margin of cartilage behind ; and they are well segmented from each other. 





1 In the Gurnards, also, the coraco-scapular band of cartilage is only partly aborted, and their 

 epicoracoid degenerates into a fibrous mass. 



