132 IVAN K. WALLIN 



A number of the 5 mm, specimens in my collection were 

 kindly given to me by Prof. C. R. Stockard. They were collected 

 in Naples. 



1 wish to take this opportunity to express my thanks and 

 appreciation to Professor Gage and Professor Stockard for this 

 valuable material. 



The specimens were fixed in various fixing fluids: Zenker, 

 formol; Gilson's, Bouin's, picro-acetic, corrosive-absolute alco- 

 hol. After being imbedded in paraffin, transverse and frontal 

 sections were cut from 4 micra to 15 micra in thickness. The 

 sections weie stained by various staining methods; methylene 

 blue and eosin, Weigert's haematoxylin and eosin. Giemsa's 

 eosin-azur, and haematoxylin (Delafield's) and eosin. The best 

 differentiation was obtained by the use of the ordinary haema- 

 toxylin and eosin method. 



A paraffined blotting paper model- of a part of the branchial 

 region of a petromyzon larva prepared by Mr. Warburton was 

 used in this study. A clay model of a part of the branchial 

 region was also prepared to facilitate the study of the arrangement 

 of the ciliated bands in the pharynx. 



COMPARATIVE ANATOMY OF THE AMMOCOETE PHARYNX 



The phylogenetic position of the lamprey is still a matter of 

 speculation. Various hypothesis have been advanced in regard 

 to its position. Some place this animal between the amphioxus 

 and the elasmobranchs, others claim that it represents a degen- 



2 A description of the method of reconstruction referred to above may be of 

 interest to workers. This method is a modification of the late Mrs. Gage's 

 blotting paper method. Sheets of blotting paper are dipped in melted paraffin 

 and dried. The drawings are transferred to the paraffined paper by the usual 

 methods when wax plates are used. The cutting is also done in the same way, 

 the knife used, however, must have a thin but strong blade. In stacking the 

 sections bank pins were used to hold the sections together. Small screws were 

 also used occasionally to give firmness. When the stacking has been completed 

 the sections may be smoothed down by means of any rounded instrument. A 

 hot iron may also be used to cement the sections together. To give the best 

 stability the complete model may be immersed in hot paraffin a few minutes. 

 Models made in this way have a great firmness and are admirably efficient for 

 class room use where a great deal of handling is necessary. 



