ECTEINASCIDIA AND THE CLAVELINID.E . 155 



2. Ecteinascidia moorei, n. sp. (PL VII, figs. 1 — 8) 



External appearance : — A number of Ascidiozooids are 

 grouped together to form a hemispherical mass (PL VII, 

 fig. 1) measuring about 3 cm. by 2 cm., and are attached 

 at their posterior ends by very slight pedicles to a short 

 branching delicate stolon which appears to have been 

 attached in its turn to sand and shell fragments. The 

 shape of the Ascidiozooids varies a little, but is nearly 

 cylindrical (PL VII, fig. 2) with a truncated anterior end 

 bearing the two sessile apertures, and a rounded posterior 

 end. The colour is a clear grey, and the body is trans- 

 parent, allowing the viscera to show through. An average 

 sized Ascidiozooid measures 1 cm. in length and 3 mm. in 

 breadth. 



The Test is very thin and transparent, and is easily 

 removed from the mantle as a delicate homogeneous 

 looking membrane. It has no vessels, and no test cells 

 are visible. 



The-Mantle is thin, but fairly muscular. All the muscle 

 bands, except on the short siphons, are transverse in 

 direction. They branch and anastomose so as to form a net- 

 work, but in their general direction all the bundles are 

 parallel. They die away on each side of the endostyle so 

 that the ventral median line has no musculature. On the 

 siphons (PL VII, fig. 3) there are powerful sphincter 

 muscles formed of a number of concentric bands, and also 

 about forty well marked radial muscles which run outwards 

 from the edges of the aperture and die away on the outer 

 edge of the sphincter. The branchial aperture is distinctly 

 6 lobed and the atrial 5 lobed (PL VII, fig. 3, at.); 



The Branchial Sac extends almost to the posterior end 

 of the body. The transverse vessels are narrow, and are 

 all of one size (PL VII, fig. 4). The internal longitudinal 

 bars are exceedingly delicate and can scarcely be seen 



