no. 363S TURBELLARIA — KAWAKATSU 11 



vesicles sacciform; sperm ducts entering bulbar cavity separately; 

 penis bulb moderate in size and muscular; penis papilla conical; 

 copulatory bursa large; bursal canal widened; common ovovitelline 

 duct entering roof of posterior part of male antrum; one to two anas- 

 tomoses of posterior intestinal trunks present; capsule oval. 



Holotype. — One set of serial sagittal sections (No. 458a: 3 slides) 

 will be deposited in the Division of Worms, Museum of Natural 

 History, Smithsonian Institution, with four whole mounts (Nos. 

 459f, 471a, 482a, 460a: head piece and one cocoon) and 34 sets of serial 

 sections (Nos. 446a, 454a-d, 455a, 458b,c, 459a-e, 462a, 463a,b, 

 464a-d, 467a-c, 475a-c, 476a, 479a, 483a-f, 485a, 486a). Some of these 

 whole mounts and sections selected from the author's collection also 

 will be deposited in that museum. 



Locality. — Lake Tahoe, Station No. 19 (holotype) and other 

 stations at depths from 15 to 1632 feet. 



Family Dendrocoelidae 



Genus Dendrocoelopsis Kenk, 1930 

 Dendrocoelopsis hymanae, new species 



Figure 4; Plate 2 



Only two specimens of this planarian, one mature and one immature, 

 are available for this description. These were collected from the 

 center of the lake (Station 23, depth 1554 to 1623 feet). As seen in 

 plate 2a, b, a small part of the left side edge in the prepharyngeal 

 region of the mature planarian was broken off; the immature specimen 

 was broken in half near the pharyngeal base in transit (pi. 2c, d). 

 These specimens were fixed but dried when received and were run up 

 into a fluid of glycerin-alcohol for about two weeks. After taking 

 photographs, I made serial sagittal sections of the mature specimen 

 and the posterior piece of the immature specimen. The head piece of 

 the immature specimen has been mounted on a slide and has broken 

 into two fragments. 



Description. — This is an unpigmented, eyeless species and meas- 

 ures up to 14 mm in length and about 2 mm in width in a preserved 

 condition. The external appearance of both the mature and immature 

 specimens is shown in plate 2a-d. The body form, however, especially 

 the shape of the head, of a living worm is unknown. 



The pharynx is situated behind the middle of the body. It is struc- 

 turally typical of the family Dendrocoelidae: its internal muscular 

 zone consists of intermingled circular and longitudinal fibres. The 

 copulatory apparatus, which could be seen vaguely from the ventral 

 side, occupies more than half the postpharyngeal region. 



