8 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 61. 



Looss, A. 1901a. Ueber die Fasciolideiigenera Stephanochasmus, Acantho- 

 chasmus und einige andere. Centralbl. f. Bakt., Parasitenk, u. lufektionskr. 

 Abt. 1, vol. 29, pp. 595-606, 628-634, and 654-661. 



Marshat^l, W. S., and Gflbert, N. 0. 1905. Three new Trematodes found prin- 

 cipally in Black Bass. Zool. Jahrb., Abt. f. Syst, vol. 22, pp. 477-488. 



OuHNEK, T. 1911. Zuni natiirlichen System der digenen Trematoden IV. Zool. 

 Anz., vol. 38, pp. 513-531. 



EXPLANATION OF PLATE. 



Allacanthochasmus varius, netv species. 



A camera lucida was employed in making all drawings. The scale accom- 

 panying the drawings in every instance has the relative value of 0.1 mm. All 

 drawings from stained toto-mounts in balsam. 

 Fig. 1. Anterior portion of a specimen viewed from ventral surface. 



2. a and b, lateral views of spines from oral circle, c, ventral view of a 



single spine. 



3. Detailed study of oral region. 



4. Oral crown fully extended and sharply marked off from remainder of 



body. 



5. Oral region of greatly elongated specimen. 



6. A very young specimen showing lateral position of testes before the 



uterus contains any eggs. 



