Manchester Memoirs, Vol. Ixii. (191 7) 35 



Bigenerina pennatula, Brady, 1884, Chall. Rep., p. 373, pi. 

 XLV, figs. 5-8. 



Rather rare. Out of sixteen specimens collected seven 

 show the uniserial manner of growth, though in only three 

 cases have more than one chamber been added on that plan. 

 This is a much larger proportion of shells taking on the 

 bigenerine growth than occurs in B. capreolus from the 

 same gatherings in which species such shells are exceedingly 

 rare, not amounting to perhaps more than \ per cent. 



(The majority of the specimens owing to their pointed 

 oral extremities and the paucity of chambers in the uniserial 

 series appear to show an affinity to B . capreolus rather than to 

 B. pennatula. The distinction between the two species appears, 

 however, to be purely arbitrary. Batsch's fig. C. is much 

 nearer to d'Orbigny's Model of B. capreolus than Brady's 

 figure of B. capreolus or Halkyard's specimens. Most of 

 Halkyard's specimens would pass unquestioned as Textularia 

 carinata, d'Orbigny, and are identical with the Maltese Miocene 

 specimens which have always been assigned to Textularia 

 carinata. The spiroplectine arrangement counts for very little 

 except as regards taxonomy. It is probable that most T extu- 

 laridce are at times spiroplectine in their initial chambers.) 



62. Bigenerina capreolus (d'Orbigny.) 

 PI. II, figs. 10-13. 



Vulvulina capreolus, d'Orb., 1826, Ann. Sci. Nat., vol. VII, 



p. 264, No. 1, pi. XI, figs. 5-8. 

 Schizophora capreolus, Schlumberger, Feuilles des Jeun. Nat., 



Aug. 1883, p. 117, pi. Ill, fig. 4, 4a. 

 Bigenerina capreolus, Brady, 1884, Chall. Rep., p. 372, pi. 



XLV, fig. 1-4. 



The specimens placed under this name might in many cases 

 be assigned to d'Orbigny's Textularia carinata, the reasons 

 against that course being the frequent compression of the later 

 chambers, which compression is always noticeable in B. capreo- 

 lus before it commences adding on its uniserial chambers. In 

 only two instances has the development been carried further and 

 an attempt made to produce a medianly situated chamber. One 

 of these specimens (PI. II, fig. 10), which is of a weak form, 

 has a narrow terminal chamber not placed on the median line 

 but excentrically. Its orifice however is similar to that seen 

 in a typical specimen. 



In favour of considering the specimens as T. carinata, 

 d'Orb. there is first, the fully developed carinate, and often 



