30 THE ROTIFERA. 



Its generic affinities are very doubtful. It is not improbable that a more matured 

 acquaintance may elevate tins strange form to the rank of a genus. In any case it is a 

 notable addition to our marine Botifera. 



Length, -fo inch. Habitat. Bock-pools, Torbay ; marine. P.H.G.] 



DIGLENA (?) SILPHA, Gosse (169), (PI. XXXI. fig. 22). 



[SP. CH. Body sub-cylindric, stouter at the head, abruptly lessened behind ; brain 

 saccate, long, opaque at the end ; toes minute, conical. 



The whole animal is very soft and plump, not wrinkled, even in retraction. A well- 

 marked, soft, decurved proboscis is on the front : no eye is visible. The sudden attenu- 

 ation of the body to a slender cylinder, one-fourth of the whole length, is remarkable : 

 this terminates in two or three soft lobes, below which are two very minute toes, with 

 no appreciable foot intervening ; for the rectum can be tiaced to a cloaca just above the 

 toes. Fuller examination is needed : I have seen but a single example, and the trophi 

 were not satisfactorily denned. Cf. Notommata forcipata, lateral aspect. 



Length, ^-^ inch. Habitat. Ireland ; lacustrine. P.H.G.] 



DIGLENA (?) UNCIKATA, Milne (186), (PL XXXIII. fig. 13). 



SP. CH. Body sub-cylindric, gibbous dorsally behind ; ciliated face oblique, and 

 overhung by a hood ; foot very short, with two very long, decurved and divergent, blade- 

 like toes ; eyes absent. 



The truncated face is covered with strong cilia ; two, or two pencils, of which are 

 more than double the length of the rest, which are themselves longer than usual. The 

 nervous ganglion is large, and below it lies an ovoid mastax, with a very formidable pair 

 of protrusile three-toothed jaws. There is a very distensible " clear-walled " oesophagus, 

 often wrinkled up, but sometimes so distended with food as to occupy half the body below 

 the mastax, and so push down the true stomach. 1 This latter has two large, flat, wedge- 

 shaped glands, each containing a peculiar vesicular hollow surrounded by two or three 

 dozen granules. The ovary is large, extending up to the mastax, and developing eggs 

 of a great size. The vascular system is normal ; at least two vibratile tags are readily 

 seen behind the mastax. Two foot-glands lie just at the insertion of the toes ; and a 

 short, fine seta springs from the " posterodorsal " surface of the foot, but is exceedingly 

 difficult to detect. " This little creature has a curious way, when moving along, of sud- 

 denly, and with exceeding quickness, switching itself back on its toe-points, head over 

 and back again, the motion being somewhat comparable, in its quickness and unex- 

 pectedness, to the springing of the Iiifusorian Haltcria grandinclla." 



The above characteristics and description have been taken from Mr. Milne's memoir 

 (loc. cit.). The author shows clearly the cloee relation between this species and the next, 

 which was described by him under the title of Pleurotrocha mustela. Like Mr. Milne, 

 I hesitate where to place these two eyeless Diglenoid Botifera ; but on the whole I agree 

 with Mr. Gosse, that their trophi and their energetic habits ought to weigh more than 

 the presence or absence of eye specks ; and that they should be placed in the genus 

 Diglena. 



Length, ^ inch. 



DIGLENA MUSTELA, Milne (PI. XXXIII. fig. 14). 



Pleurotrocha mustela Milne (188). 



SP. CH. Like the preceding, but with very short toes. 



There are one or two other points in which the two species differ. The gastric 

 glands, in mustela, are pyriform, and attached to the (true) stomach by long stalks. 



1 See Triopthalmus <lorsnafif, p. 32. 



