27G SIDNEY P. HAllMER. 



10. S. truncata, n. sp. Figs. 9, 36, 37. 



S. magnilabris, Busk, 'Challenger Report/ pt. xxx, 

 1884, p. 75 (Port Dairy inple) ; MacGillivray, in 

 McCoy's ' Prodr. Zool. Vict./ vol. i, decade 6, 

 1881, p. 43, pi. Ix, fig. 1; and 'Trans. Roy. Soc. 

 Victoria,' xxiii, 1887, p. 208. 



B zooecia hardly larger than a zooecia. Cryptocyst descend- 

 ing rather steeply, without angulation, to join the distal wall 

 at or below half its height. Median process well developed, 

 usually with rounded distal angles, and with deep cavity into 

 which the cryptocyst descends steeply, the roof of the tube 

 being visible in its floor. Opening of tube oblique, entirely 

 visible from above, completed by the distal wall, or complete 

 and separated by a narrow portion of the cryptocyst from the 

 distal wall. Oral shelf well developed in both a and b, not 

 tubercular. Oral arch of B semicircular, of A truncate, and 

 usually slightly concave distally. B-opercula very strong, 

 with A-shaped main sclerite, and with about twenty sub- 

 marginal teeth, all except a few of the proximal ones being 

 stout, long, and nearly erect. A opercula transversely oblong-, 

 with rounded, corners ; a strong tooth on the main sclerite 

 not far on the distal side of the occlusor tubercle, and a 

 strong basal sclerite. 



(ft) Victoria (Port PhiUip, etc.), Miss E. C. Jelly (C. M., 

 24.5.95). 



(h) Victoria, Hincks Collection (CM., 13.5.99). 



{c) Victoria, Prof. W. Baldwin Spencer (CM., 1899). 



[d] Port Dalrymple, Tasmania, voyage ''Rattlesnake," 

 Busk Collection (B. M., 51.9.29, 34). 



The name which I suggest for this well-marked species is 

 in allusion to the truncate form of the a zooecia (fig. 9). 

 By this character (already noticed by MacGillivray), and the 

 shape of the opercula with their dark brown sclerites, the 

 species can be recognised at a glance. The two large teeth 

 of the a opercula distinguish it at once from any other species 



