184 F. Chapman and Irene Grespin : 



We have much pleasure in naming this species after Dr. Thomson, 

 who has already done so much in regard to the description of our 

 rhynchonellids. 



Occurrence. — Miocene (Janjukian): — " Cras satellites bed," Table 

 Cape, Tasmania. Type from the Dennant Collection. 



4. — Tegulorhynchia antipoda, Thomson, sp. 

 Hemithyris antipoda, Thomson, 1918, p. 117. 



Description. ^l^hQ following definition is taken from Dr. Thomson's 

 notes, as recorded above. The shell is of the same size as nigricans 

 and squamosa. It is distinguished primarily by the character of the 

 ribs. They are similar in size to H. nigricans^ but are rather more 

 numerous, and are incipiently spinous. To this we may briefly add 

 the above species appears to be near T. thomsoni, but differs in the 

 shape of the beak, and in the stronger growth-lines. 



Dimensions. — Length, 20 mm.; breadth, 22 mm.; thickness, 11 mm. 



Occurrence. — Miocene. Type locality, Curiosity Shop, Rakaia 

 River, Canterbury, New Zealand. 



5. — Tegulorhynchia imbricata, Buckman, sp. 



Hemithyris imbricata, Buckman, 1910, p. 11, pi. I., fig. 12 



Description. — (Ventral valve). "Broadly pentagonal, ornamented 

 with numerous, somewhat stout, rounded radial, costae, which are 

 crossed by growth-lines somewhat conspicuously; and where the cross- 

 ings occur there is imbrication — the test of the rib being raised into 

 an incipiently spinous projection. The ribs increase in number by 

 intercalation, and by bifurcation, at irregular distances from the beak. 

 The new rib so produced is of smaller size at first than the older 

 ones, so that there is some irregularity of ribbing. There is a dis- 

 tinct mesial sinus." 



Observations. — Buckman draws attention to the affinities of this 

 species, with T. doederleini, Davidson, sp., the living Japanese form 

 with hollow spines. It also shows some relationship with our new 

 species, T. coelospina, described below. P'rom the latter, T. imbrHcata 

 differs in having finer costae, more transverse shell, and a more 

 depressed sinus on the ventral valve. 



Occurrence. — Miocene. Glauconitic Bank, Cockburn Island, off 

 Graham Land, Antarctica. 



6. — Tegulorhynchia, coelospina, sp. nov. PL I., fig. 7; pi. III., fig, 25. 



Description. — Shell subcircular, beak fairly prominent, erect. In 

 the type specimen, deltidial plates obscure, but seen in other ex- 

 amples to be triangular and strongly built; slightly discrete. Umbo- 

 of dorsal valve acute. Shell depressed, the valves showing almost 

 equal convexity. Sinus and fold little pronounced. Plicae about four 

 on ventral sinus. Costae about twenty-two on margin of valves. 

 Bufurcation of the costae takes place in the later stages. The growth- 



