Nnr and Ho re Fossils. 187 



the i.rniiiinciit l)c;ik jiimI tlir ahsriut' of a inesial i'ol<l on tlie lirachial 



valvr. 



(;,.,.„,.;.,,„.,.. _B,.ie 11. 4:5()-4;5-2 feet. 



Tkiikhkatklla poejilaxdica, .sp. iiov. (Plate X\'lll., Fii;s. SGttc,. 

 37, 38). 



Descri ption. — Shell small. roTindly oval : outline subanguhtte. 

 Valves plano-convex. Beak small, pointed, foraini'ii conspieuous : 

 surface of pedicle valve strongly arched dorsally ; Itrachial valve 

 with a shalloAV. bi-oad sinus, not extensive, turned doAvn to meet 

 the arched fold of the pedicle valve. Sliell surface finely punctate.. 

 and showing a few faint concentrii- lines tending to l)ecome lami- 

 nate. 



Dimensions. — Length of holotype. 5.75 mm.: width. 5 nun.;, 

 thickness, 2.25 mm. 



Ohserrations.- — This interesting little Terehratclln is not infre- 

 quent in the bores, but never abundant. Iti only two cases were 

 perfect examples secured, on account of the lial)ility of the valves 

 to easily separate. By its well-developed median septum it is seen 

 to be a typical member of this genus. The above species is of the 

 TerehrateUa woodsi type.l but that shell is much heavier, having a 

 larger foramen and comparatively gigantic beak, and with a deepei- 

 and more convex brachial valve. At first sight T . porihnidira might 

 be confused with Tate's Magasello hmafa.^ which also occurs in 

 these bores, but may be distinguished by the latter having a typical 

 acute beak with smaller foramen, characteristic of that genus, and 

 a rounder outline to the shell. 



In the Dennant collection there is a ty))ical example of the above 

 species from Portland, which was doul)tfully referred to Terehra- 

 teUa woodni. and in the same tube are numeious shells of a similar 

 form from Beaumaris. My attention was first directed to this 

 particular species some years ago in the Nati(mal .Museum collec- 

 tion, when sorting over material from the white polyzoal limestiuie 

 of Portland, at which locality it is a typical fossil. 



Occurrence.— Yi(^\e 6, lU-150 feet; 154-158 feet. Bore 9. 263- 

 273 feet. Bore 10. 254-296 feet; 310-320 feet. Bore 11. 505-510 

 feet: 515-520 feet ; 525-530 feet : 545-55(1 feet. 



Loo supra cit. 



Trutis. K. Soc. S. Aiist, vol. xxiii.. 180f>. ].. 



