ENCHYTR^EID^E 



43 



3, (XIII) 5, 6, 5, 4, 5, 5, 6, 6, (5, 4, 3, 3, 2, 2) ; ventrals, 6, 7, 7, 

 7, 7, 7, o, (XIII) 4, 7, 6, 5, 4, 5, 6, 5, 4, 3, 2. Head-pore far for- 

 ward. Clitellum XII-XIII. Copulative papilla insignificant. Septal 

 glands in IV to VI. Brain broader than long, posteriorly truncate. 

 Spermatheca short and broad, lopsided, with two short diverticles at 

 the center. Sperm-ducts short, as long as the funnels. Funnels long 

 and narrow. Penial atrium long and rather narrow. Three or four 

 long atrial glands enter this atrium outside of the penial bulb. Some 

 five or six penial glands inside of the bulb opening near the penial 

 orifice. Ovaries and testes in XII and XI. Two large and very long 

 sperm-sacs connecting with the funnels extend backward some fifteen 

 or more somites. Nephridia rounded, with shallow lobes. Nuclei 

 slightly oval. Lymphocytes unknown. Color of alcoholic specimens 

 pale yellowish. 



Locality. Port Clarence, Alaska. A single specimen, collected 

 by Prof. Trevor Kincaid, August, 1897. 



Characteristics. This species is readily distinguished by the short 

 spermathecae, which are peculiarly lopsided, one diverticle being 

 thicker than the other. The short sperm-ducts are also characteristic. 

 Owing to want of specimens the detailed description given below is 

 naturally meager. Part of the single specimen was dissected, part 

 sectioned transversely. As 

 will be seen, the species be- 

 longs to the group of Mes- 

 enchytraeids with atrial 

 glands. These glands are 

 larger than in M. fuscus. 

 They are also less numerous 

 than in that species, its 

 nearest relative. 



DETAILED DESCRIPTION. 



Spermathecce (fig. 18, 

 a and b). Both sperma- 

 thecae showed a peculiar 

 lopsidedness. 



Sperm-ducts (pi. ix, fig. 

 2). These are less than 

 one-eighth as long as the 

 funnel. The penial bulb extends nearly to the end of the atrial en- 

 largement in the dissected specimen. In the sectioned half it appears 

 to extend to the middle of the atrium. 



FIG. 1 8. Mesenchytrceus penicillus. 



