BY G. I. PLAYFAIR. 811 



tapiealibus interdum insequalibus et eontortis; nonnunquam 

 granulis vel costis brevibus in serie. uniea paullo infra fossam 

 transversa^ ornata. Cetera ut in forma typiea. 



Long. 44-51, lat. 34-46, epiv. alt. 23-27, crass. 23-27 ^ 



Centennial Park (133) ; Botany (17) . 



The hypovalve in this form is very irregular behind, more 

 faceted and with plates concave; the antapical plates are some- 

 times (but not always) unequal and contorted. There is occa- 

 sionally a single row of granules or of short costae below the 

 margin of the transverse groove. (PL xlii., f. 3) . 



Var. truncatum, n. var. (PL xlii., f. 1, 2) . 



Forma hypovalva pone truncata, lateribus areuatis . Cetera ut 

 in f. typiea. 



Long. 51-52, lat. 42-49 ^ Botany (17) ; Lismore (327) . 



Another common form; it is more or less truncate behind, with 

 rounded sides to the hypovalve. The larger specimens in all 

 these forms seem to be proportionately broader and less oval 

 than the type. The striae are generally faint, but occasionally 

 quite distinct, when they appear as rows of partly coalesced 

 granules or scrobieulae, probably the latter. 



Var. acuminatum, n. var. (PL xlii., f. 4). 



Forma modo irregularis; epivalva magis acuminata. 



Long. 52, lat. 46 ^ Centennial Park, Sydney (133) . 



A rather irregular form with epivalve more pointed above. 

 The transverse furrow is generally slightly spiral in all the forms, 

 its breadth in the specimen measured was 5-6 p, of the longi- 

 tudinal furrow 6-10 p, the rhomboidal plate seems to be entirely 

 coalesced with the latter. 



Var. auburnense, n. var. (PL xlii,, f. 5-7) . 



A forma typiea differt solum in membrana per longitudinem 

 levissime costata, inter costas late reticulata. 



Long. 45-57, lat. 40-53, epiv. alt. 24-30 fi. 



Auburn (148) ; Centennial Pk. (133) ; Lismore (297, 302, 308). 



A very curiously marked form, first noted at Auburn (Sydney). 

 The membrane is lightly costate longitudinally, the spaces be- 

 tween the costae being filled in with an irregular lattice work of 

 reticulations. The same series of forms may be noted with this 

 membrane as with the striate. 'Var. auburnense is abundant 

 round Lismore and numerous specimens were measured, so that 

 the range of dimensions for this form may reasonably be taken 

 to represent those of the whole species. Transverse furrow 



