EEPORT ON THE NEMERTEA. 49 



presence of true ova in the fragments, which proved to have belonged to a female 

 individual, definitely excluded the possibility of any confusion on this head. 



The cjuestion arises, whether the peculiar appearance of the difierent tissues recorded 

 above might be pathological, and somehow in causal relation to the infesting parasites. 

 It is this which necessitates extreme caution in the identification of these fragments. I 

 may here remind the reader that another case, presumably of a parasitic organism (also 

 unicellular, but of much smaller size) infesting the difierent tissues, was met with in 

 Amph iporus raarioni. 



The last fragmentary sj^ecimen which I wish to record may, for all I know, have 

 belonged to the common Cerehratiilus marginatus. It was collected in the Atlantic 

 Ocean, at Station 321, off the Brazilian coast. It was a very large and flattened speci- 

 men, but without head or tail. In M'Intosh's notes I find these fragments referred to as 

 foUows : — 



"Two fragments, respectively 70 and 108 mm. in length, and with a transverse 

 diameter ranging from 21 to 24 mm., the vertical (in the centre) being only 5 or 6 mm. 

 The dorsal surface was dull ohve, with a dark median band, the greater part of the 

 breadth being marked by fine transverse strise, leaving only the borders untouched. 

 Various transverse fines, passing quite across the body, also occurred ventrally. The 

 median line and the borders had each a smooth belt, the rest being marked by the closely 

 arrane-ed and tranverse lines. A median ridoe occurred along the ventral band." 



The ova of this species, polygonal by reciprocal pressure, and surrounded by a gela- 

 tinous outer layer (capsule), are figured on PI. XV. fig. 18. 



(ZOOL. CHALL. EXP. — FART LIV. — 1887.) Hllh 7 



