BY F. BLOCHMANN. 115 



1913. 



Dimensions in miUimet)'t»s. 



Largest example. Example figs. 8,9. 



Length 12-0 10-5 



Breadth 11 ... 93 



Thickness ... 60 5-5 



Habitat, off Cape Pillar, Tasmania, at a depth of 180 m. 

 <100 fathoms). 



3. Argykotheca (Cistella) Mayi, d. s}-. (Phite xi., 



fig. 10, 11.) 

 Outline, nearly rectangular, broadened more or less to- 

 -v^rards the front, so that the outline is nearly triangular. 

 The front edge is slightly indented. Both valves have a 

 slight median-sinus. Hinge line nearly straight. Dorsal- 

 valve is perforated. Beak very short and broad ; beak 

 •edges sharp. Adjoining these towards the middle is a flat 

 ^rea. Stem hole very wide, bordered on the side by very 

 narrow deltidial plates, and in front by the edge of the 

 hinge. The ventral valve is quite flat, the dorsal a good 

 deal arched. In the ventral valve a moderately high 



median-septum reaching beyond the middle. In the 



dorsal valve a median fujTow, bordered on the sides by a 

 low ledge, sinks down from the hinge border nearly to the 

 middle of the valve. Where the furrow ends a high, 

 thick, median-septum ai'ises, reaching quite to the edge of 

 the valve, and the base resting upon the valve is about 

 double the length of the free edge. The ciTira are short 

 and broad, with pronounced crural prolongations. The 

 descending limbs attach themselves, after a short course, on 

 the inner surface of the valve, and disappear. On each 

 side of the lower part of the side surfaces of the septum 

 arises a small band descending to the surface of the valve, 

 a renmnnt of the anu-lcop. Number of pores in the pq. mm. 

 about 200. Diameter of the outer opening of the shell- 

 tube, 15-1 7m. 



Dimensions in millimetres. 



Length 2-5 



Breadth 2 



Thickness 1-0 



Habitat, about 18 km. (10 miles) east of Schouten Is- 

 land, East Coast of Tasmania. Depth, 145 m. (80 fathoms). 

 Only empty shells were obtained. This species is certainly 

 ■distinct from the Argyrotheca (Cistella) australis (Tnms. 

 Roy. Soc. S. Aus., Vol. xxxiv., 1910, PI. xxvii , figs. 10-12), 

 formerly described by me, also from all other known species. 



