18-2 "TERRA NOVA" EXPEDITION. 



oblique foramen. Part of a deltidial plate remains, and is separated from the rounded 

 flanks of the beak by a sharp edge. There is also a slight pedicle-collar. The inner 

 surface of the valve shows traces of two parallel furrows down the middle, such as are 

 seen in shells of Liothyrella urn [see Jackson, 1912, pi. i, fig. 9 ; and Fischer and 

 Oehlert, 1892, pi. viii, fig. 23]. 



The other specimen, B. (PI. I. fig. 1 B), measures: length, 35 mm.; width, 

 about 30 mm. It is pyriform, with its maximum width anterior to the middle. Valve 

 convex, and deepest in the umboual area. The beak has rounded flanks and is 

 truncated by an oblique, oval foramen, which possesses a labiate prolongation over the 

 conjoined deltidial plates. Outer surface with somewhat coarse growth-Hues, but no 

 radial striae are apparent ; interior surface quite smooth ; slight pedicle-collar. 



It is possible that both specimens, A and B, belong to the same species. 



The absence of the dorsal valve renders a description of the cardiualia and 

 brachidium impossible. That the species belongs to the short-looped forms, however, is 

 clearly evident from the presence in the ventral valve of a feature known only to exist 

 in short-looped species, viz., a pedicle-collar. In a recent paper [Jackson, 1916] 1 called 

 attention to the fact that in some twenty-four recent and a number of fossil species 

 of short-looped forms which I had examined, a true pedicle-collar* was universally 

 present. This feature does not appear to be developed in any of the higher long-looped 

 forms such as : Magellania, Terebratella, Dallina, Macandrevia, Terebratalia, etc., etc. 

 This fact seems to provide a useful criterion for separating, into their right group, odd 

 ventral valves, when other evidence is not available. 



The shell-substance of the New Zealand specimens, A and B, when viewed under the 

 microscope, is seen to be tunnelled in every direction by very fine burrows, presumably 

 made by organisms similar to those found in Compsothyris racovitzce (see p. 190), and 

 it is difficult to get even ygth of a square mm. without these. Consequently it 

 is almost impossible to study the puuctse and shell-mosaic in a satisfactory manner. 

 This is all the more unfortunate as there is much yet to learn regarding punctatiou. 

 The shells are undoubtedly very finely and densely punctated, the number of pores 

 per square millimetre, as far as can be ascertained, ranging from 272 to 304 (six 

 counts on the same specimen yielded 288). 



The species has a striking resemblance to some of the forms of Liothyrella itr<i,j 

 figured and described from the Magellauic region, viz. Falkland Islands (Burdwood 

 Bank), South Georgia, and South Orkneys, as well as from the West Antarctic. 

 Perhaps the most striking resemblance, however, of this New Zealand species is to the 

 geographic variant of L. uva, viz., var. tiotorcadensis, described by me in 1912 from 

 Scotia Bay, South Orkneys [compare PL 1, tig. I, with Jackson, I'.) 12, pi. i, figs. 1-3]. 

 The general form is similar and there is the same curious labiate prolongation of the 



* The "doublure sous-apicale " and "doublure sous-cardinale " of Fischer and Oehlert [1891, pp. 44, 

 103, etc.]. 



| This species also has tine radial strue on the surface of the valves. 



