328 E. GROVE AND G. STURT ON 



guishcd as " var. major " ; in other respects similar. From five 

 to seven vein-like lines in pairs are given off from the margin, and 

 the pseudo-nodules are distinct. The valves exhibit, most strik- 

 ingly, the peculiar areolar appearance. Distance between the 

 angles, •0067 ,/ . Frequent. (PI. XIX, Figs. 15, 1G.) 



T. lobatum, Grev. (<< Q. J. M. S.," Vol. hi, N.S., p. 233, PI. 9, 

 Fig. 13). — Rare, but identical with Greville's form. 



T. denticulatum, Grev. (" Q. J. M. S.," Vol. iii, N.S.,p. 233, PI. 

 9, Fig. 14). — Pare, closely resembling the type. 



T. inelegans, Grev. var. ("T. M. S.," Vol.xiv, p. 8, PI. 2, Fig. 

 21). — This variety closely resembles the var. micropore/, Gran, (in 

 " V. H. Synop.," PI. 110, Fig. 3), but the granules are fewer 

 and more scattered. Distance between the angles, *0022". Pare. 



T. unguiculatum, Grev. (" T. M. S.," Vol. xii, p. 85, PI. 11, 

 Fig. 9). — Frequent. The processes are very slender, and bent out- 

 wards, giving, in some positions of the valve, the appearance of 

 the claws delineated in Greville's figure. 



T. nitescens, Grev. (" T. M. S.," Vol. xiii, p. 8, PI. 2, Fig. 19). 

 — Very rare, but identical with Greville's species. 



T. Weisii, Grun. (Witt " Simbirsk," p. 34, PI. 7, Fig. 9, and 

 PI. 12, Fig. 3). — A small form, very scarce in the lightest density. 



T. americanum, Ralfs. (" Pritch.," p. 855 ; Schm. " Atl.," PI. 

 76, Fig. 27). (N.B. In the " Atlas " T. americanum and T. conde- 

 corum have been transposed, Fig. 27 being T. americanum, Fig. 

 28 T. condecorwn.) — A variety of this form occurs sparingly, and 

 has great affinity with T. parallelum. Some valves have very 

 concave sides. A quadrangular form, " var. quadrata," also 

 occurs with concave sides, and an umbilicus of small puncta 

 arranged in a circle. Distance between the angles, -0036". This 

 variety in its aj)pearance closely approaches Stictodiscus ; for the 

 present we leave it here. 



T. cwlatum, Janisch (Schm. "Atl.," PI. 81, Fig. 19).— The 

 original example we have not seen ; so it is with hesitation that 

 we identify this form, which is somewhat rare, with Janisch's 

 species. The valve is nearly flat, with straight sides and radiating 

 granules, which are scattered at the centre, but at the margin are 

 arranged in close-set parallel lines. Distance between the angles, 

 •0083". 



T. DohreZanum, Grev., var. nova Zealandica, n. var., Gr. and 

 St. — This form, not uncommon in the deposit, is more ornate than 



