:^02 KE(;ORDS OF THE AISTHALIAN MUSKl'M. 



in the left valve iiuniediately beneath the prodissocunch there 

 descends obliquely into the valve a prominent thickened ridge, 

 above which is a deep narrow groove, followed by the margin of 

 the valve, which is broadly i-etlected on the umbo ; anteriorly the 

 chondrophore is followed by a slight ridge ; in the right valve a 

 thickened posterior tubercle and a slight anterior groove ; no 

 lateral teeth occur ; the muscular impressions, as is usual in so 

 thin a shell, are invisible ; inner margin of valve smooth and 

 bevelled. Length, 60 ; height, 5 ; depth of single valve, 

 1 -5 mm. 



Besides the present station the species occurs in 250 and 300 

 fathoms oft" Sydney. The indi\idual figured was obtained in the 

 former station by Mr. W. F. Petterd and> myself. 



0. sfinirddiata, Tate, was assocated with ('. rifrotis, both off 

 Narrabeen and Sydney. 



ECTORISMA fJRANULATA. Tate. 



Ectorismo qramdata, Tate, Trans. Hoy. Soc. S. Austr., xv., 1892, 

 p. 127, pL i, f. 3, 3rt. 



This species was represented by a \ ah e and some fragments, 

 which latter indicate that the shell attains a length of 20 nmi. 

 Examples were recently submitted to Dr. W. H. Dall, who in- 

 forms me — 21 Sept. '06 — that it is a Foromya, and Tate's genus 

 therefore unnecessary. The specific name is already occupied by 

 Nyst in this genus, and if otherwise unnamed the species requires 

 another designation. The species, howe^ er answers fairly to the 

 description of Porumya l(crif<, Smith," obtained in 155 fathoms 

 oft' Raine Island, N. Queensland. So that until actual compari- 

 son can be made it seems better to use Smitli's name iov our shell 

 than to coin a new one. 



LVONSIKLLA (^UADKATA, Sp. HOV. 



(Plate Ivi., figs. 31, 32, 33). 



Shell small, thin, inflated, oblong, the posterior side much 

 longer than tlie anterior. Umbo much incurved. Sculpture : 

 irregular faint growth lines are crossed by a few inconspicuous 

 radial furrows, one of which, running from the umbo to the pos- 

 terior ventral angle, is cut deeper than its fellows ; except round 

 the umbo, whei e they have perhaps been worn away, small close- 



s' Smith— Chal. Rep., Zool., xiii., 1885, p. 55, pi. xi., f. 3. 



