93 



The form has been closely compared with examples of 

 Magellania flavescens of the same size, and is immediately 

 distinguished from them by its general shape, and especially 

 by the very differently-shaped beak, and by the complete 

 absence of ribs, which are already quite plain in really 

 small examples of M. flavescens. Again, in the formation 

 of the brachial apparatus distinct differences present them- 

 selves. By the general form, one might be reminded of 

 young examples of M . lenticularis (the illustration of David- 

 son, Recent Brachiopoda, pi. ix., figs. 2 to 13), although this 

 is not yet known from the Australian coast. But against 

 this likeness are the much more strongly hook-shaped curved 

 beak in the last-named form, the very small diameter of the 

 inner orifices of the pores (scarcely 10 /x), and the quite dis- 

 tinct pattern on the valves. Also, the brachial apparatus 

 of the young figured example of Davidson is quite different. 

 So it remains only to regard the examples before us as repre- 

 sentatives of an independent new species. 



Cistella australis, n. sp., Blochmann. PI. xxvii., 

 figs 10 to 12. 



Shell as long as broad. Colour dirty-yellow. 



Length and breadth are equal, thickness amounts to 

 about one-half of this. Because the dorsal valve is bounded 

 behind by a straight hinge-line, it approaches a semicircle in 

 outline. The complete outline is altered by the triangular 

 beak. The end of the beak is flatly rounded. Its edges are 

 sharp. Between them and the hinge-line is a flat area. 

 Deltidial plates seem wanting. The hole of the beak is large, 

 bounded towards the front to a considerable extent by the 

 hinge-margin of the dorsal valve. 



Each valve bears a moderately conspicuous median 

 sinus, and on each side of this three ribs, increasing rapidly 

 in width towards the periphery. These project at the edge 

 as rounded teeth, so that if the posterior corner is included, 

 four rounded teeth are found at the edge, on each side of the 

 notch corresponding to the median sinus. These are not 

 always quite distinct, so that the edge often appears only 

 flatly undulating. Also, variations occur between the right 

 and the left. The growth striae in both valves are quite dis- 

 tinct. Both valves are about equally deep. There are about 

 320 pores to the square millimetre ; inner diameter of these, 

 about 10 /x; outer diameter, about 15-20 /i; frequently oval, 

 20 p by 10 ,x. 



The edge of the pedicle hole forms a conspicuous collar. 

 In the ventral valve is found an indistinct median septum 



