100 PROCEEDINGS OF THE ACADEMY OP [1879. 



the base of this papilla three to five low septula diverge, divide 

 and go to the base of the plumes aud their broad rhachides. 1 The 

 veil entire (not bilobed) ; with the upper border (about 8 mm.) and 

 the corners (about 10 mm.) freely projecting (fig. 13); it is (36 

 mm.) broad and (16 mm.) high; on the front side regularly fur- 

 rowed by fine reticulated lines, which produce the appearance of 

 a serpent's skin (PI. IV. fig. 5); the upper edge of the veil is 

 smooth or showing only traces of dentition ; 2 there is no trace of 

 the grooved fold on each side at the base of the veil found in the 

 Tr. Hombergi; the end of the muzzle beneath the middle of the 

 veil is contracted. The sides of the body somewhat high and con- 

 vex, a little lower in the anterior part; decreasing in height from 

 the region of the anus backward. The upper genital opening was 

 entirely filled by the flagelliform penis (PI. III. f. 13d) which was 

 about 20.0 mm. long, with a diameter at the base of 3.0, and at 

 the tip of 0.5 mm. The larger mucous gland (fig. 13) was below 

 this opening. Behind the middle of the body is the crateriform 

 anal papilla projecting about 3 mm., in the orifice of which are 

 strongly projecting folds (PI. III. fig. 15a) before which is the 

 renal opening also provided with internal folds (fig. 156). The 

 foot is as long as the back, rounded in front, with a marginal 

 groove which extends beyond the region of the genital orifices ; 

 the foot projects laterally some 3-4.0 mm. from the body. The 

 tail is short, hardly 3.0 mm. long. 



The peritoneum is colorless, the viscera not in the best preser- 

 vation in the specimen examined. 



The central nervous system closely resembles that of the Tri- 

 tonia Hombergi, 3 the limits of the two compartments of the cerebro- 

 visceral ganglia are more pronounced than in the Tr. Hombergi; 



1 The representation of the rhinophoria of Frit. Hombergi, by Alder and 

 Hanc. (1. c. part vii. 1855, fam. 2, pi. 2, fig. 2) is too simple. 



2 Pallas mentions and represents the veil as "lacero-dentatura." 



3 The representation given by Alder and Hancock, as well as that of 

 Ihering (Vergl. Anat. der Nervens. und Phylog. d. Moll., p. 174, Taf. II. 

 f. 6) are nearly correct, at least in the essential characters ; the short com- 

 missure between the cerebro-visceral and the pedal ganglia is of course 

 double, as seen by Ihering, and perhaps also represented by Alder and 

 Hancock, on the left side ; in the hinder part of the left visceral and pedal 

 ganglion is a small ganglion communicating with the visceral one ; the 

 gastro-cesophageal ganglia are shorter-stalked than represented by A. 

 and H. 



