412 Mr. ft. A. Baylis on 
strongly coiled tail, and are provided with two spicules, 
which, though small, are easily seen in cleared specimens. 
These spicules (figs. 1 and 2 B) are unequal in length, 
measuring 0°62 mm. (left) and 0°3 mm. (right) respectively. 
They are completely covered externally with small rough 
granulations. _ Hach spicule is considerably expanded at its 
proximal end and blunt distally. . 
The tails of both sexes show a very marked difference in 
size between the ‘ Terra Nova’ and Mr. Bennett’s specimens. 
In the male (fig. 2) the distance from the cloacal aperture 
Big, 
Crassicauda crassicauda. The two spicules of the male, seen from the 
left side. 
to the tip of the tail is about three times as great in the 
former as in the latter. In the female (figs. 3 and 4), in all 
cases and in both species, the curious constriction in the region — 
of the vulva, described and figured by Creplin, is well-marked. 
The vulva (figs. 3 A and 4, v.) lies. towards the anterior end 
of the constriction, and the caudal end assumes the shape of a 
rounded or oval knob. ‘he anus (figs. 3 A and 4, a.) lies 
in a depression at the posterior end of the latter. According 
to Creplin’s figures, the terminal knob would measure 5 mm. 
in length in an exceptionally large specimen. Leiper and 
