ENCHYTR^ID^ 



93 



MARIONINA AMERICiVNA sp. nov. 



p1. XIV, fig. I ; text-figs. 6i and 62. 

 Definition. — Length 10 mm., width .5 mm. Somites about 50. 

 Prostomium blunt. Setae : ventrals, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, o, 2, 

 4, 4, 4, etc. ; laterals, 2, 2, 2, 2, 3, 2, etc. Head-pore immediately 

 in front of the groove between prostomium and somite I. Clitellum 

 small, XII and XIII. Sexual papillae small, cylindrical, truncate. 

 Brain posteriorly slightly emar- 

 ginate ; posteriorly much broader C!!^.^ « 



than anteriorly. Dorsal vessel 

 rises posterior to clitellum. In- 

 testine with few and thin chlo- 

 ragogen cells. Spermathecae 

 consist of a narrow and com- 

 paratively long duct, and a short 

 and wide ampulla furnished with 

 two short diverticles ; the am- 

 pulla does not seem to connect 

 with the intestine. The penial 

 bulb contains two kinds of gland- 

 ular cells, one kind being more 

 granular and staining more 

 deeply than the other. Sperm- 

 duct narrow and coiled, confined to XII and XI. Testes entire, but 

 covered by a cap-like sperm-sac confined within XI. No ovisac. No 



ventral glands. Lymphocytes large, round- 

 's----^ ed, disk-like. Color pale, without pig- 

 ment. 



Locality. — Port Clarence, Alaska, Dr. 

 Anton Stuxberg, Vega Expedition (July 

 23 to 27, 1S79). A single specimen. 

 Characteristics . — The single specimen 



„.-,.. . being in a poor state of preservation pre- 



FlG. 62. Mariomna americana. » ^ .... 



vented any detailed investigation. The 

 anterior part of the worm was sectioned transversely. The nephridia 

 are not in a sufficient state of preservation to allow their finer struc- 

 ture to be satisfactorily studied. The spermatheca is distinctly char- 

 acteristic of the species. 



Setce. — The setae of the ventral fascicles diminish in size toward 

 the ventral interval, while those of the lateral fascicles diminish toward 



rionina americana. 



