262 MESSRS. E. HERON-ALLEN AND A. EARLAND ON THE 



range of variation in the specimens which have to he referred to this species. At ninny 

 Stns., notahly Stns. 2, 4, and 20, the specimens in their regularity of growth approach 

 C. cymboides, d'Orb., and C. acutauricularis. At Stns. 3, 12, and 20 large individuals 

 of the compressed type of C. arcuata, d'Orb., occur. The majority at all Stns. are 

 megalospheric, but microspheric specimens occur at Stns. 17 and 18. The size of the 

 primordial chamber influences the later growth of the shell in the genus Cristellaria 

 perhaps mure than in any other. 



232. Cristellaria acutauricularis (Fichtel & Moll). 



Nautilus acutauricularis, Fichtel & Moll, 1798, TM. p. 102, pi. xviii. figs. g-i. 

 Cristellaria acutauricularis, Brady, 1884, FC. p. 543, pi. cxiv. figs. 17 a, b. 



5 Stations. 



Occurs at very few Stns. and nowhere typical. All the individuals are of a narrower 

 type, as viewed across the face of the terminal chamber, than in Fichtel & Moll's original 

 plates. They thus approach C. cymboides, d'Orbigny. At Stns. 4 and 20 some of the 

 specimens were almost typical C. cymboides. This species has only been recorded as a 

 recent British form by us from Clare Island and the North Sea (H.-A. & E. 1913, CI. 

 ]). 99, pi. viii. fig. 15), but Wright has recorded it from Post-tertiary deposits in the 

 North of Ireland (W. 1910-11, ECM. p. 15). It has probably been included by many 

 authors under C. crepidula, which, as Burrows and Holland have observed (Proc. Geol. 

 Assoc, vol. xv. 1897, p. 40), has been made to include a very wide series of varieties. 



233. Cristellaria COnvergens, Bornemann. (Plate 42. figs. 11-14.) 



Cristellaria convergens, Bornemann, 1855, FSH. p. 327, pi. xiii. figs. 16, 17. 

 Brady, 1881, FC. p. 54G, pi. lxix. figs. 6, 7. 



2 Stations. 



At Stn. 4 two minute and thin-walled specimens of a Cristellaria were found, which 

 we are inclined to refer to Bornemann's species, and a single one at Stn. 20. 

 Bornemann's figures are in themselves unsatisfactory, fig. 16 representing a rotulate 

 form with no visible septation ; whereas fig. 17 represents a form evidently allied to 

 C. gibba and having marked septal lines. His fig. 18 (on same plate), C. elliptica, 

 illustrates a form linking figs. 16 and 17, and C. elliptica is properly regarded as a 

 synonym of C. convergens. 



The two ' Buna ' specimens represent the two types figured by Bornemann in his 

 figs. 16 and 17, but, as might be expected in such shallow water, the specimens 

 are small and the shell-texture thin and extremely hyaline, so that the septation is 

 distinct in both individuals. 



C. coucergens is normally a deep-water type. Brady's records range between 16 and 

 27 i i Ems., the majority being in the neighbourhood of the 2000-fm. line. As a recent 

 British sprcies it has only been recorded by Pearcey from the Firth of Forth (Trans. 

 Na 1 1 1st. Soc. Glasgow, NS. vol. v. 1900-1, p. 242). 



