1904.] OSTEOLOGY OF THE ELOPID^ AND ALBULIDiE. 79 



branchials are set close together, without the usual interval. The 

 fourth and fifth basibranchials are represented by an undivided 

 plate of cartilage, as is customary in Teleostean fishes. No trace 

 of ossification is to be detected in this plate, a fact which is of 

 interest in relation to the discovery by Swinnerton of separate 

 ossified fourth and fifth basibranchials in that aberrant and 

 specialised genus Cromeria (Zool. Jalirb., Abth. f. Anat. sviii. 

 1903, p. 66). 



The hypobranchials are much reduced in the Mormyroids, and, 

 as already pointed out, the second hypobranchials are confluent 

 with prominent tendon-bones. In Coilicc and Engrmdis the 

 second hypobranchials are fused with the sides of the second 

 basibranchial, and in Chanos the third hypobranchials are fused 

 with the third basibranchial, bvit in each case the suture remains 

 visible. 



The " spicular bone " is generally taken to represent the 

 modified first pharyngobranchial. In Hyoclon the first pharyngo- 

 branchial bone is large, and is certainly upturned and rod-like, 

 resembling a spicular bone ; but in all the forms examined which 

 have a true spicular bone this arises from the upper surface of the 

 first epibranchial, and not from its anterior end as it does in 

 Hyoclon. In Chirocentrus the first pharyngobranchial is a conical 

 bone projecting forward and upward. In Albula it is a bone which 

 runs forward with its axis in a line with that of the first epi- 

 branchial, and is clearly serially homologous with the second and 

 third pharyngobranchial s. In Mo7-myrus and Mormyrops^ also, 

 there is a small ossified first pharjmgobranchial, but as a rule this 

 element of the visceral skeleton is caitilaginous. 



The above-mentioned genera appear to have no true spicular 

 bone, but in Engraulis, Clu2:>ea, Chaioessits, and Chanos there is a 

 cartilaginous fii'st pharyngobranchial and a true spicular bone in 

 addition, while in Elops, Megcdops, and Alepocejjhcdtis there 

 is a well-defined and fully ossified first pharyngobranchial as 

 well as a slender spicular bone. The simultaneous presence of a 

 spicular bone and an unmistakable first pharyngobi'anchial bone 

 effectually disposes of the argument that the spicular bone repre- 

 sents a modified first pharyngobranchial. The spicular bone has 

 the value of an ossified ligament for the attachment of the 

 branchial skeleton to the side of the pro-otic, and is not a primary 

 constituent of the viscei'al skeleton. The confusion which has 

 arisen with respect to it, is probably due to the fact that in some 

 cases — it is not yet possible to say whether they are many or few — • 

 the first pliaryngobranchial takes upon itself the suspensory 

 function of the real spicular bone. The long bone which in the 

 Berycidse and Oyttidse is attached to the anterior end of the first 

 epibranchial appears to be a true first pharyngobranchial, but 

 fui-thei- obser'vations upon the relations and the development of 

 this bone are much to be desired. 



It is frequently diflicult to say whether a bone of the bi-anchial 

 skeleton is really toothed or not, since in cases where teeth are 



