84 THE ROTIFEKA. 



Genus PAEASEISON, Plate (192). 



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

 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 ^- inch. Without true corona, but with 

 four tufts of tactile setce, standing round ike buccal aperture. 



PABASEISON NUDUS, Plate (192). 



SP. CH. Size V inch. Head without any trace whatever of a corona ; and also 

 without buccal tactile seta. It also becomes attenuated in front ; so that the buccal 

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



PAEASEISON PEOBOSCIDEUS, Plate (192). 



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

 but with a small proboscidiform eversion of the skin, seated above the buccal aperture, 

 which serves as a tactile organ. Hare. 



Length, ^ inch. 



PAEASEISON CILIATUS, Plate (192). 



SP. CH. Assists in the transition to the genus SEISON, inasmuch as the corona is 

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

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



Length. About ^ inch. 



Genus SACCOBDELLA, Van Beneden and Hesse (1G2). 

 SACCOBDELLA NEBALLE, 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-like group. In 

 the North Sea. 



Length. From T V to inch. 



M. A. F. Marion (114) says that Nebalia Straiissii 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 Nebalice, when they are 

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



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

 lamina of 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- 



