140 E. GROVE AND G. STURT ON 



by two conspicuous parallel rows of cellules. Forms with two pro- 

 cesses are not infrequent. Diam. -006". (PI. XI, Fig. 29.) 



The main distinction between A. beeverice and A. rattrayii is that 

 the latter bas an hexagonal cellulation, whilst the former is charac- 

 terized by distant radiating lines of large pearly granules. 



A. comberi (Arnott), var. oamaruensis, Gr. and St. — Valve 

 moderately convex, and not so lurid in colour as the type form. 

 Processes, in the few specimens observed, three ; small, oval, sub- 

 marginal. Margin striated. Cellules about 9 in -001", with a 

 small clear umbilicus, and a small clear space at the base of each 

 process. Furrows distinct. Diam. about '007". Scarce. 



A. elegans, n. sp., Gr. and St. — Valve with convex edges and 

 rather flat upper surface. Cellules hexagonal, papillate, about 10 

 in -001", merging into dots at the centre, where there is usually a 

 small circular clear space. Processes in the specimens observed, 

 5, 6, or 7, narrow, prominent, cylindrical. No clear space at the 

 base of the processes. Furrows represented by the walls of two 

 adjacent parallel lines of cellules. Scarce. Diam. about '007". (PL 

 XII, Fig. 30.) 



A. huttonii, n. sp., Gr. and St. — Valve with convex centre and 

 an undulation between centre and margin. Processes, usually four, 

 papilliform, submarginal, projecting vertically. Cellules granular, 

 large, confused in the middle, but passing into distinct radial lines, 

 which are very conspicuous towards the margin. Surface between 

 the granules delicately punctate. It has an irregular clear um- 

 bilicus and distinct furrows, which widen as they approach the 

 processes. Not scarce. Diam. -004". (PL XII, Fig. 31.) 



A. convexus n. sp., Gr. and St. — Valve oval, very convex, with 

 hexagonal cellules, about 10 in •001", papillate with an umbilical 

 group of larger cellules. 



Processes three, submarginal, enlarged at the end in a spathulate 

 form, springing from a small clear space. Longest diam. about 

 •006". Scarce. (PL XII, Fig. 32.) 



A. cellulosus, Gr. and St., var. plana. — Differs from the type form 

 in being less convex, and having (in all specimens yet observed) 

 four processes only. Not very scarce. Valve usually about *008", 

 in diam. 



A. radiosus, n. sp., Gr. and St. — Valve large, moderately convex, 

 with a small circular umbilicus of cells, the rest of the surface 

 being covered with minute hexagonal cellulation, about 9 in '001", 



