THE CnONDROCRANIUM OF SEBASTES MARINUS. 501 



27. The Chondrocranium of the Teleosfcean Fish Sehastes 

 marinus. By N. A. Mackintosh, B.Sc, Demonstrator 

 in Zoology, Imj)erial College of Science, South Ken- 

 sington * 



[Received May 8, 1923 : Read June 12, 1923.] 



(Text- figures 1-9.J 



CONTKNTS. 



Page 



1. Introduction 5oi 



2. Material and Method 502 



3. The Cliondrocranium 503 



a. Stage 1. The unhatched embryo 503 



6. Stage 2. The 4'5 mm. larva 504 



c. Stage 3. The 5-5 mm. larva 505 



rf. Stage 4. The 25 mm. stage 507 



4. Summary 512 



5. Aljbreviations , 513 



6. Literature 5I3 



1. Introduction. 



The work of Parker and subsequently that of Glaupp, Bolder, and 

 others, on the skull of Salmo, constitutes the basis of our knowledge 

 of the cranial development of the Teleostomi. Further contri- 

 butions have been made by Stohr, McMurrich, Allis, Winslow, 

 Swinneiton, and Pehrson amongst others. In 1910 Allis pub- 

 lished a paper dealing in some detail with the cranial anatomy of 

 the mail-cheeked fishes. Tliis jiaper dealt with the osteology, 

 and to some extent the latero-sensory canals and muscles of the 

 adult cranium, but, so far ns I am aware, no work hns so far been 

 (lone on the development of the cartilaginous skull of any of the 

 Scorp.'enidaj. It is hoped that the present paper will take a step 

 towards meeting this deficiency in that it describes the chondro- 

 cranium of a fairly representative member of the group. 



The following description is not an exhaustive comparative 

 account, and few generalizations will be made ; it deals with the 

 development of the chondrocranium from a very early stage up 

 to the time when the cartilaginous elements of the head are 

 fully developed. Certain comparisons with other forms will be 

 made where points of special interest or peculiarity arise. 



The work was undertaken at the suggestion of Prof. MacBride 

 and I wish to take the opportunity of thanking him and 

 Mr. H. G. Cannon for many helpful suggestions. 



* Coniniunicatcd by Prof. E. W. MacBbide, F.R.S., F.Z.S. 



33* 



