250 62 



teristic of the female, are wanting. I have been unable to find any retro-cerebral 

 organ, but there is a very conspicuous dorsal antenna, furnished with two nerves. 

 The brain is large, carrying the large red eye. No lateral antennæ are seen; as 

 RoussELET however has found them in some of the other species, thej' maj' possibly 

 be present here too. There are seven or eight conspicuous transversal bands and 

 powerful retractors of the wheel-organ. Above the testis is a large sac of different 

 form, ending below the brain and reaching the penis behind. In the sac is always 

 found a different number of rather large oil globules; in my opinion we here have 

 a very conspicuous rudiment of the alimentary canal. There are two lateral canals 

 which, in the specimens I have observed, seem to reach the brain. This is of interest, 

 as the canals in the female sex do not reach much more than half-way into the bodj' 

 cavity. The canals carry four vibratile tags; there is no contractile vesicle, the canals 

 opening on each side of the penis. The testis is very large of different form and size, 

 provided laterally with two small prostata glands; the penis is remarkably small 

 with a tuft of hairs at its base. There are two conspicuous foot glands. Size : Male 

 160 /(. Female 300 fx. 



Synchæta tremula Gosse. 



.Male: Gosse 1856, p. 321. 



Hudson-Gosse 1889, p. 128. 



Rousselet 1902, p. 283. 



Tab. Ill, fig. 2. 

 GossE (1856 p. 321, PI. XV, fig. 30—31) has given a short description which, together with 

 the drawing, makes it verj' probable that he has really observed the male: An obconical 

 form with rounded front, set with long cilia. A red eye, sharply defined, a central granular 

 viscus, contained in a longitudinal cavity, in the bottom a large, irregular opaque white mass. 

 The foot seemed to carrj' a great protrusile penis and to terminate in two minute toes. Size 

 '/s'o in. HuDsON-GossE (1889 p. 128 PL XIII, fig. 2) have seen a glimpse of a male and also state, 

 that they have seen the four stj'li on the coronal head. 



Rousselet (1902 p. 283, Tab. Ill fig. 3 a). It is a small conical creature with a bent to- 

 wards the ventral side, close behind the head. The front is truncate, with four stjdes. The 

 red eye, dorsal antenna, large sperm sack and two acute toes are prominent. The masta.x and 

 stomach are quite absent, and replaced by the sperm sack. Size 110,«. October. 



Description. The male of S. tremula is most probably indistinguishable from 

 S. pectinata. We find the same conspicuous rudiment of intestine (denied b}' Rousselet 

 1902, p. 283). It must only be pointed out that the foot is much smaller, only a 

 small tap with inconspicuous toes but well-developed foot glands; it is perhaps placed 

 more ventrally and the penis is somewhat more prominent. Size of male 120 ^if, of 

 female 250. — Time: May. 



Synchæta oblonga Ehrbg. 

 Male: Rousselet 1902, p. 287. 

 Rousselet (1902 p. 287, Tab. Ill, fig. 2a). The discription and figure of the male are not 

 so plain that it can be distinguished from that of S. tremula. 



