[77] 



THE OSTEOLOGY OF AMIA CALVA. 



823 



membrane, and the ramus of the mandible thus formed articulates with 

 the squamosal bone in mammals, but in other vertebrata is immovably 

 united with the os articulare. Hence the complete ramus of the mandi- 

 ble articulates directly with the skull in mammals, but only indirectly, 

 or through the intermediation of the quadrate, in other Vertebrata''^ 

 (Anat. of vertebrated animals, p. 28, 29). Many of the Teleostei have 

 various muco-dermal bones attached to, or connected with the skull, 

 such as the chain of " supertemporals " that overarch the temporal fossa 

 in some fishes. The most important of these in Micropterus, a pair on 

 either side, I propose to call the supralinear ossicles (si), as they overlie 

 the anterior end of the lateral line. The largest and most external of 

 these is shaped like a T, the ends of the horizontal portion resting on 

 the squamosal on one hand, and the posttemporal on the other. The 

 vertical limb is directed inwards and a little forwards, having attached 

 to it by ligament the second piece, directed still a little more anteriorly. 

 In the living bass these bones are easily detected, lying just beneath 

 the skin in the lateral line as it arches over the temporal region. 



OF THE SHOULDER GIRDLE OF AMIA CALVA. 



My description of the girdle ofAmia will be ^^resented pari passu with 

 that of Micropterus salmoides, the Teleost we have chosen for comparison 

 in the skull as given above. The nomenclature of the various segments 

 of this part of the skeleton is a matter of great importance, and without 

 entering into any discussion upon this point, I propose here to adopt 

 that of Professor Gill, as set forth in his Arrangement of the Families 

 of Fishes, published by the Smithsonian Institution (November, 1872). 

 Dr. Gill very tersely gives his reasons for departing from the older au- 

 thors on this subject in the introduction of this valuable and classical 

 paper. It is not necessary for me to repeat his remarks here, as they 

 are now well known to ichthyotomists generally, having been in the 

 hands of scientists for many years. 



As the two tables Dr. Gill presents, however, are of great value, 

 and will add so much to my remarks in the present connection, it 

 gives me much pleasure to introduce these here. This eminent ichthy- 

 ologist first treats of the girdle in Dipnoans, and says in review that 

 '• the homologies of the elements of the shoulder girdle of the Dipnoi 

 appear then to be as follows " : 



IN'omenclattire adopted. 



Owen. 



Humerus. 



CORACOID (or Pahaglenial). 



Scapula. 



ECTOCORACOID (or COEACOID). 



Sternum. 

 Posttemporal. 



Humerus. 



>Coracoid. 



Scapula. 



Parter. 



Humerus. 



Scapula. 



Supraclavicle. 



Clavicle. 



Epicoracoid. 



Posttemporal. 



Giinther. 



Forearm. 

 Humeral cartilage. 



> Coracoid. 



Median cartilage. 

 Suprascapnla- 



In this table I have omitted certain foot notes and quotations con- 

 nected with it. As to "The Girdle in other Fishes" Dr. Gill remarks 



