422 PROCEEDINGS OF THE NATIONAL, MUSEUM vol.86 



ing fold into a larger male portion containing the penis papilla and a 

 smaller female portion of tubular shape, which continues above into 

 the bursa stalk and opens below by the common genital pore. Nu- 

 merous gland cells open into the female atrium, mostly from behind, 

 some from in front below the penis, and many of them accompany the 

 terminations of the oviducts and open into the bursa stalk where the 

 oviducts open. Female atrium lined with a tall epithelium and clothed 

 externally with a thick layer of intermingled circular and longitudinal 

 muscles continuous above with tlie muscle layer of the bursa stalk but 

 thicker than this and passing ventrally into the regular subepidermal 

 muscle layer of the body wall. 



Locality. — Isla de la Sol, Lake Titicaca, Bolivia, collected on 

 February 18, 1936, by M. C. James. 



Type. — As serial sections, U.S.N.M. no. 20402. 



Remarks. — It is rather peculiar that all the fresh-water planarians 

 so far known from South America (listed by Fuhrmann, 1914b, who 

 also describes some additional species) belong to the genus Dugesm 

 except ^''Planaria^'' patagoiuca Borelli, 1901, which apparently belongs 

 to Curtisia. The Dugesm species are very similar in external appear- 

 ance and anatomy of the copulatory apparatus; hence they are not 

 easy to distinguish. D. titicacaiia most nearly resembles D. festae 

 (Borelli, 1898), also found in high mountain lakes, in Ecuador. The 

 principal feature wherein D. titicacami differs from other members of 

 the genus is the form of the penis papilla, with its central depression 

 bearing a papilla on which terminates the ejaculatory duct. 



Family DENDROCOELIDAE 

 Genus SOROCELIS Grube, 1872 



SOROCELIS AMERICANA, new species 



Figures 47, d, e; 48, a 



Mateiial examined. — Seven preserved specimens, all asexual, prob- 

 ably not fully grown. 



Description. — Maximum length, 5 mm, width 1.8 nun, somewhat 

 contracted, hence longer and less plump in life. General external 

 appearance shown in figure 47, d. Head truncate, center and mar- 

 gins slightly projecting, giving a wavy effect; the central projec- 

 tions contains the adhesive organ; the lateral projections corre- 

 spond to auricles. Eyes numerous, in a lengthwise arc on each 

 side of the brain, each arc composed of 10 to 20 eyes (fig. 47, e). 

 Brain large, of elongated quadrangular shape, giving off numerous 

 branches forward and laterally and the usual two ventral cords pos- 



