84 THE ROTIFEEA. 



Genus PAEASEISON, Plate (192), 



Both sexes without intestine. Corona as in Seison, or reduced to a few tactile setffi, 

 or entirely wanting. In the hind head only two flask-shaped glands, which open into 

 the oesophagus, in the commencement of the neck. Sexual organs in male and female 

 placed laterally or dorsally to the stomach ; only exceptionally displaced below it. Each 

 lateral canal with five vibratile tags, and giving off a thin-walled, coecally terminating, 

 lateral branch, in the anterior part of the trunk. The ductus ejaculatorius of the male 

 with smooth walls, with no movements or lateral organs, with numerous flask-shaped 

 spermatophores. The foot does not terminate with an adhesive disc, but the hind 

 extremity of the foot has the form of a hemisphere beset with a row of small denticles, 

 between which the viscous glands discharge themselves. In the Bay of Naples. 



Paeaseison asplanchnus, Plate (192), (PI. XXXIII. fig. 22). 



SP. CH. Average size of the adult female J,,- inch. Without true corona, hut with 

 four tufts of tactile seta, standing round the Mwcal aperture. 



Paeaseison nudus, Plate (192). 



SP. CH. Size ^ffj- inch. Head ivithout any trace whatever of a corona ; and also 

 ivitlwiit buccal tactile setce. It also becomes attenuated in front ; so that the buccal 

 aperture comes to he situated at the apex of a small cone. 



Paeaseison peoboscideus, Plate (192). 



SP. CH. Head without any trace of corona, ivithout tactile seta at the mouth, 

 hut with a small jjroboscidiform eversion of the skin, situated above the buccal aperture, 

 which serves as a tactile organ. Bare. 



Length, -^^^ inch. 



Paeaseison ciliatus, Plate (192). 



SP. CH. Assists in the transition to the genus Seison, inasmtcch as the corona is 

 developed as in that genus ; and further there are, on the ventral surface, tivo longitu- 

 dinal streaks composed of numerous parallel muscular fibres. Not uncommon. 



Length. About ^-g inch. 



Genus SACCOBDELLA, Van Bcneden and Hesse (162). 

 Saccobdella nebali^. Van Beneden and Hesse (162), 



The abdomen terminates in two pedunculate sucking discs. Neck composed of five 

 segments of about equal length. Foot of four rings. Buccal aperture on the lower 

 surface of the head, not far from the anterior margin. The intestine is said to traverse 

 the whole body in the median line. Colour of the body a very light blue. The ova 

 possess a small stalk, and several of them may be united to form a bush-hke group. In 

 the North Sea. 



Length. From ^V to ^ inch. 



M. A. F. Marion (114) says that Nebalia Straussii lives shut up, in July and August, 

 in the voluminous mass of the rudimentary capsules of Murex brandaris ; and that 

 Saccobdella adheres to the foliated branchial feet of the young Nebalia, when they are 

 in the " poche incubatrice " imder their mother's carapace. 



Parascison, according to Dr. L. Plate, attaches itself, by preference, to the branchial 

 laminae oi Nebalia, but also creeps about on all other regions of the body. It attaches 

 itself by the adhesive secretion of its foot-glands ; and, as there are not unfrequently 

 several ova lying together (in one case there were eleven) in different stages of develop- 



