1 86 F Chapman and Irene Crespin : 



less number of costae, and in the beak being a little more prominent. 

 We have enlisted the good services of Professor Sir Douglas Mawson 

 in endeavouring to find the original specimen, that we might examine 

 it, but it has not come to light. As we have gone into the matter 

 of the identity, or otherwise, of the fragment, with Tate's type, we may 

 note that our conclusions are in favour of the probability of there 

 being two specimens the type evidently having been perfect. Since 

 Tate records his type from Muddy Creek, polyzoa-1 rock series, it is 

 interesting to note that the Dennant specimen came also from the 

 same bed. The differences between this form, and the previously 

 •described T. coelospina are in the depressed valve of the latter, and 

 the coaser and fewer tubulated costae. 



We have been favoured by Mr. Cudmore with a fragmentary valve 

 •of a rhynchonellid, presumably from the Lower beds of Muddy Creek, 

 and this we have figured. It appears to approach most nearly T. tuhU' 

 lifera^ but differs in some respects, and may point to the existence 

 •of an additional species in our series. 



Occurrence. — Oligocene. (Balcombian). Lower beds. Muddy Creek. 

 Miocene. (Janjukian). Polyzoal Rock, junction of Grange and Muddy 

 •Creek. 



9. — Tegulorhynohia doederleint, Davidson, sp. 



Rhynclionella doederleini^ Davidson, 1886, p. 1, text-fig. 19. 

 Rhynchonella doederleini, Davidson, 1887, p. 172, pi. XXV., figs. 

 14, 15. 



Description. — " Shell transversely subpentagonal, wider than long; 

 hinge-line obtusely angular. Dorsal valve deep, posteriorly uniformly 

 convex, anterior divided into three lobes, the central one forming a 

 broad rounded mesial fold varying in elevation according to the age 

 of the individual. Ventral valve much less deep than the dorsal one, 

 with a broad mesial sinus or greater or less depth, commencing at a 

 third of the length of the shell, and extending to the front. Beak 

 moderately produced, almost erect, with an oval-shaped foramen situ- 

 ated under its gently incurved angular extremity, and margined by 

 narrow deltidial plates. Lateral margins of the valves slightly sinu- 

 ated, and forming in front a more or less elevated curve. Surface 

 of valves marked with numerous delicate radiating ribs, with inter- 

 spaces between them of almost equal width, and increasing in number 

 at variable distances from the beaks by the interpolation of shorter 

 riblets. Ribs numbering, in full-grown specimens, sixty, close to the 

 margin. Valves closely crossed by numerous equidistant, concentric, 

 raised or foliated lines of growth, giving rise at the margin of each 

 riblet to short sloping or erect hollow spinules. Shell structure fibrous. 

 Colour, light yellowish grey. In the interior of the dorsal valve are 

 two short curved lamellae for the support of the labial appendages." 

 Dimensions. — "Length, 12 lines; breadth, 13; depth, 7 lines." 

 Observations. — This living species was compared In its spinosity 

 to the Jurassic "Rhynchonella'' spinosa by Davidson, i^ and was later 



14. Davidson, 1886, p. 2. 



