420 H. B. POLLARD, 



On the relations of Chlatnydoselachus to Bolypterus. 



These relatioiis may, thanks to the descriptions of Garman and 

 Aters, be here summarized in a list: 



(1) The mantle fold over the gills is a structure from which 

 the operculum and opercular fold of Pohjpterus may be 

 derived. 



(2) The mouth is terminal. 



(3) The nostrils are laterally placed occupying an exactly ana- 

 logous position in Osteolepis (Pander), 



(4) Maxillary teeth are present more numerously massed to- 

 gether at the angle of the mouth. In the Crossopterygidae 

 esp. Osteolepis and Pohjpterus the maxilla is most massive 

 and extensive posteriorly. Here is a phylogenetic stage 

 confirming what Hertwig deduced from ontogeny — that 

 bones are formed from tooth bases. 



(5) The slime canals show such a distribution as to allow the 

 derivation of the Polypterine arrangement from them. 



(6) The disposition of the scales suggests the formation at 

 ridges on the tail and fins of fulcra and fin rays. 



(7) Teeth extend down the pharynx and over the gills as in 

 Folypterus. 



(8) The primordial cranium shows similarities with Folypterus 

 especially in the low occipital crest and in the snout, the 

 latter point applying especially to fossil Crossopterygidae 

 {Osteolepis). 



(9) The Conus arteriosus shows 6 or 7 rows of valves. In 

 Folypterus the number, 9, is very great. 



(10) Precardiac dorsal aorta is present. 



(11) The fin may well be considered an ancestral form of the 

 Polypterine fin. 



Some further relations with the Urodelcs. 



Elsewhere I have given some account of the auditory organ as 

 I was not aware that it had been already described. Perhaps I may 

 be allowed here to express my sincere apologies to Prof. Retzius 

 for not acknowledging his priority. It is not now necessary for me 

 to publish my drawings for it was a great satisfaction to me to learn 

 how closely they agreed with those of Prof. Retzius (Biol. Untersuch. 

 Leipzig 1881). There is a small otolith in the recessus utriculi. In 



