4 1 6 . HOPKINS. [Vol. XI. 



glands and epithelium of this group, and those by only a few 

 observers. To certain of the Ganoids no reference whatsoever 

 was found on this subject. 



Material and its Preparation. 

 The forms upon which this paper is based are as follows : 



Family Acipenseridae. 



Acipenser rubicundus. (Common Lake Sturgeon.) Scaphirhynchops platy- 

 rhynchiis. (Shovel-nosed Sturgeon.) 



Family Polyodontidae. 

 Polyodon folium ? (Spoon-billed Sturgeon, Duck-billed Cat.) 



Family Lepidosteidae. 

 Lepidosteus osseus. (Gar-Pike, Bony Gar, Bill- Fish.) 



Family Amiidae. 

 Amia calva. (Bowfin, Dog-Fish, Mud-Fish, Lawyer, Johnny Grindle.) 



The material was obtained and placed in the hardening fluid 

 immediately on the spot where the various forms were taken. 

 Specimens of the common sturgeon, Polyodon, and Scaphi- 

 rhynchops were obtained in the month of February (or the very 

 first of March) from Knoxville, Tennessee. Other specimens 

 of Polyodon and those of Lepidosteus were taken in the latter 

 part of August from the Mississippi River at Ft. Madison, 

 Iowa. 



The material was preserved by hardening in picric alcohol 

 (95/0 alcohol, I part; water, i part; picric acid, \f) from- one 

 to two days; then it was placed in G'j'jo alcohol for a day, after 

 which it was kept in 82% alcohol. When needed for use, 

 small pieces from various regions of the enteron were dehy- 

 drated in 95% alcohol for one day, then soaked in chloroform 

 twelve to twenty-four hours, after which they were infiltrated 

 and embedded in paraffin. Mercuric chlorid was also used as 

 a hardening agent with very satisfactory results. The fresh 

 tissue was placed in the solution of mercury (HgCb, 5 grams; 

 NaCl, Yi gram; H2O, 100 cc.) for one-half to two hours — a 



