236 W. N. F. WOODLAND 



blood-sucking animals, extremely minute, and this leads into 

 a short, very narrow, though distensible channel opening into 

 the thick-walled (when empty) elongated pharynx (ph) which 

 extends posteriorly as far as the transverse nerve-commissure 

 (nc). This pharynx is capable of great distension (PI. 18, figs. 4, 

 c, d). Its wall, when not distended, is of considerable breadth 

 and is transversely striated, and I believe is covered externally 

 by a layer of cytoplasm containing relatively few nuclei (judging 

 from the appearance seen in one of my specimens, on which 

 fig. 5 is based) ; but of this I am not quite certain, and Dr. Plehn 

 may be correct in stating that nuclei are absent in this region 

 of the gut. In most preparations it is difficult to distinguish 

 such nuclei from the nuclei of the layer of muscle-cells (PI. 18, 

 fig. 1, PMUs) which is connected with the outer wall of the 

 pharynx. From the posterior end of the pharynx to the gut 

 sac is a narrow oesophagus (oe), with a wall much thinner than 

 that of the pharynx and covered externally with a layer of 

 nucleated cytoplasm. The oesphagus apparently lies ventral 

 to the nerve commissure. The gut sac (gs), situated at the 

 hind end of the anterior third of the body, is somewhat irregular 

 in shape, but is more or less compact and possesses none of the 

 distinct four or five lobes figured by Plehn. Its wall consists 

 of a thin, occasionally nucleated, layer of granular cytoplasm. 

 Dr. Plehn, in her first description ^ of Sanguinicola as a Turbel- 

 larian, naturally regarded the anterior canal and sac as a gut ; 

 but she states that it only contains a ' feinen Brei ' and that 

 blood-corpuscles are never found in the lumen, because the 

 mouth and anterior canal are too narrow to admit of their 

 entrance. But the mouth and all parts of the canal are capable 

 of considerable distension, as is shown in my specimens, and in 

 two cases I have found distinct rows and small masses of 

 evident fish blood-corpuscles in the anterior end and hind part 

 of the pharynx and in the sac. There is thus no question con- 

 cerning the gut-nature of the anterior canal and sac, and this 

 fact definitely settles the non-Cestode nature of Sanguinicola. 



* "Sanguinicola armata und inermis (n. gen. n, sp.), n. fam. 

 Rhynchostoniida. Ein ento-parasitischer Turbellar im Blute von 

 Cypriniden ", ' Zoologischer Anzeiger ', Bd. xxix, p. 244, 1905-6. 



