496 



test appear to be of secondary importance in the classification. Fre- 

 quently they sustain conclusions reached from a consideration of other 

 characters. 



Classification. 



It is perhaps desirable that the classification adopted (although 

 having to do with so few species) should be put in tabular form. No 

 apology need be offered for the proposal of new names. Advance in 

 classification can be made only by the formation of new divisions and 

 references to new divisions are greatly simplified when the divisions bear 

 names. Old names have been retained wherever possible, the diagnosis 

 being altered. Names have not been given to all the divisions but only 

 to those which seem to deserve the rank of genera or subgenera. For 

 the most part this synopsis has been restricted to species that I have 

 examined myself. Some species have been included which I have not 

 examined but which it has been possible to place with some degree of 

 certainly. Each of these has been marked with an asterisk (*). 



Aj. Gonads few and large. 



Testes attached to the body wall separately from the ovary (Fig. VI, 

 also III and IV). 



Atrial velum narrow, its inner surface covered with tentacles 

 (Fig. XII, 1). 



Siphonal spinules well developed. 

 Anus with distinct lobes. 



Bj. Testes negatively stereotropic, elongated in a direction per- 

 pendicular to the plane of the body wall, their lobes diverging 

 (Figs. VIII and IX, also upper two of IV). 

 Ci. Ducts of gonads opening near anus and atrial siphon 

 (Fig. X, left side). 



Genus Styela Fleming. Type, — 8. canopus (Sav.). 

 Four pharyngeal folds on each side. 

 Aperture of dorsal tubercle curved. Open interval directed 

 forwards or to left. 

 Two or more gonads on each side. 

 Spinules truncate or pointed (Fig. XIII, 5). 



Section I. 



Normally two gonads on each side. Surface of body 



smooth or rough, sometimes longitudinally furrowed. 



In this section there are 5 short species, — *S. canopus 



(Sav.), *S. variabilis (A. and H.), *S. canopoides Heller, 

 S. partita (Stimps.) and *S. pupa Heller; one elongated 



