',^Q{y Afbani/ Miisniiii Recoirh. 



TRIGERIA, liaylf. 



Tri(j('ri(i. s//ii////:r, iiov. S|). 



PI. VI I., Fig. 1). 



The specimen I make the type of this species was compared 

 with Mr. Reed's Trige/-/agaud/'i/i\ Oehlert, but though the general 

 similarity of the cast is very marked, there are differences which 

 are specific. The specimen now to be described is the cast of the 

 brachial valve, and shows the median rib wider but not otherwise 

 distinguished from the lateral ribs. The first three lateral ribs con- 

 verge towards the prominent adductor scars. The ribs are low, 

 separated by furrows of about the same width and depth and 

 interrupted by two rings of growth. I can only count 17 ribs in 

 all, making the shell to have originally had about 21. Had there 

 not been such a strong resemblance to the shells which Mr Reed 

 had named Trigeria gaudryi, I should have compared this 

 present form wWh Betzia /anies/((n«}i'dvti^, C ntroneUajaiiiet^iand. 

 of Katzer. 



In a large slab of grey sandstone from Montagu there 

 are a number of shells, both brachial and jiedicle valves, which, 

 however, are too poorly preserved to show the margins ; the 

 median fold in the brachial valve tapers i-apidly towards the umbo 

 and has a slight furrow down the centre, and the median furrow 

 on the pedicle valve is similar, with a central fokl. The best pre- 

 served specimens show Ij ribs, but a few more may have existed 

 in the original shell : there is another vai'iety on the same slab 

 with still fewer and more strongly marked ribs. I believe these 

 forms must be the same as the Tngerid siinplcr from the Gydow 

 Pass. 



Dimensions : Length, 0.75 cm. Breadth uiicei'tain. 



Cat. No. 2589. Type, Donor : Geological Commission. Locality, 

 Gydow Pass. 



Cat. No. 79. Donor: Dr. W. G. Atherstone. Locality, 

 Montagu. 



I Ou the Devonian Brachiopoda of Even-, Biazil, Bull Buffalo Acad. 

 Nat. Sci., 1874, p. 243. 



