ENCHYTR^EID^E 35 



tending to VII or VIII ; does not connect with the intestine. The 

 spermathecal pore surrounded by a large circular white field, exceed- 

 ingly prominent. Sperm-ducts narrow. Sperm-funnels of medium 

 size. Atrium with several atrial glands opening into the lumen outside 

 the penial bulb. The penial bulb with many large penial glands (com- 

 plex) opening around the penial pore ; also numerous single glandular 

 cells. A set of smaller glands, confined to the inner and lower part of 

 penis, open in the penial lumen at the pore. Sperm-sacs large, 

 double, extending far back. Spermatophores present in the sperm- 

 sacs, but not in the spermathecae. One ovisac. Nephridia large, two- 

 lobed, with some inner ciliated ducts. Lymphocytes small, ovoid 

 or ellipsoidal ; cyanophil with erythrophil nucleus. Color dying 

 yellow, with the anterior somites deep brown dorsally, due to 

 pigment. 



Locality. Popof Island, July 13, 1899, Prof. Trevor Kincaid. 



Characteristics. This species resembles greatly Mesenchytrceus 

 obscurus, but differs in the following particulars : In M. maculatus 

 nearly all the atrial glands open in the same plane, and the terminals 

 of the ducts open in pockets between the epithelial cells. The brain 

 is deltoid. In M. obscurus the atrial glands open, each one, almost, 

 in a different plane, and the terminals do not open in pockets. The 

 brain is broader than long. In j\f. obscurus the diverticles of the 

 spermathecae are much longer in proportion to the balance of the 

 organ than in M. maculatus. In M. obscurus the large shield around 

 the spermathecal pores is wanting. The two species are undoubtedly 

 distinct, though closely related. 



DETAILED DESCRIPTION. 



Body (pi. v, fig. 4; and text-fig. 14 a). The upper parts of 

 the anterior somites strongly brownish, much more than appears from 

 pi. v, fig. 4, the manner of illustration not permitting of sufficiently 

 heavy shading. The head -pore an oblong, narrow, transverse slit, 

 situated near the apex of the prostomium. The body strongly taper- 

 ing posteriorly. Besides the general pigmentation of the anterior 

 somites, several parallel brown lines reach from head to tail. Four of 

 these lines run along and surround the fascicles of seta3, the two other 

 lines passing throngh the spermathecal pores. All through the body 

 there is much pigment deposited in the peritoneum. 



Brain (fig. 14 c). Only two posterior retractor muscles, but 

 anteriorly two muscles extend toward the apex of the prosto- 

 mium. 



