STICHOCOTYLE NEPHROPIS, A NEW TREMATODE. 279 



a series of small suckers on each side. They are very numerous, and all of the 

 same size. In Octocotyle * there are, near the aboral extremity, four pairs of 

 lateral suckers, one pair behind the other. The suckers of Gastrocotyle t form 

 a single series along the edge of a projecting membrane on the right side of the 

 body. Ernst Zellek describes a serial repetition of pairs of suckers as an 

 occasional abnormality in Diporpa. j At the posterior extremity of this genus 

 there is a pair of large suckers forming divergent projections. Zeller met 

 with a specimen in which the single pair was replaced by three pairs, one 

 behind the other. In all these cases the suckers are provided with chitinous 

 hooks, as in nearly all the Polystomidae. Stichocotyle is without chitinous 

 armatures in any part of its body. Until the adult form is found and its 

 anatomy examined, it is impossible to say anything more definite about the 

 position of Stichocotyle than that it belongs to the Polystomidae, though it 

 differs from all other Polystomidae in passing through an encysted stage within 

 the body of another animal. 



I hope before long to trace out the whole life history of this interesting 

 form, as at the Granton Marine Station I shall have good opportunities for 

 carrying on the search after its earlier and later stages. In concluding the 

 present account I have to express my warmest thanks to Dr Arnold Lang, of 

 the Naples Zoological Station, who kindly sent me some valuable suggestions 

 and references. 



EXPLANATION OE PLATE XXXIX. 



Letters of Reference. 



his. Cord of blastema. 



ci. ca. Ciliated tubules of water-vessel system. 



co. Spherical concretions in lateral canals. 



ep. Epidermis and cuticle. 



e. ap. External aperture of water-vessel system. 



/. ce. Free cells in lumen of intestine. 



;//. Openings of dermal glands (?). 



int. Intestine. 



int. ep. Epithelium of intestine. 



I. ca. Lateral canals of water- vessel system. 



me. Mesenchyma. 



mu. su. Muscles of sucker. 



m. Mouth. 



me. gr. Granules in mesenchyma. 



ne. Cerebral ganglion. 



ph. Pharynx. 



su. Series of suckers. 



te% ch. Terminal chamber of water-vessel system. 



* Van Beneden et Hesse, Mem. Acad. Roy. de Belg., Tom. xxxiv. 



f Ibid. 



% Zeits. f. wiss. Zool., 13 d. xxii. 1872. 



