Manchester Memoirs, Vol. Ixii. (191 7) 17 



Genus Hauerina, d'Orbigny. 



27. Hauerina fragilissima (Brady). 



PI. I, fig. 2. 



Spiroloculina fragilissima, Brady, 1884, Chall. Rep., p. 149, 



pi. IX, figs. 12-14. 

 Hauerina fragilissima, Millett, 1898, Journ. Roy. Micro. Soc , 

 p. 610, pi. XIII, fig. 8, also 9 and 10. 



This species is not rare in my collections, though on 

 account of its fragility it is rarely found perfect. Both the micro- 

 spheric and the megalospheric forms are present. Of the former 

 I show a transverse section. It will be seen that in the earlier 

 portion of this form there is an apparent arrangement of the 

 chambers in seven radial series before the shell takes on the 

 spiroloculine manner of growth. If, however, the section is 

 examined more closely it will be found that the chambers are 

 really arranged in two involved opposed curves as in 

 Sigmoilina but in a more complicated manner as each series 

 consists of about 2.\ turns, after which it adopts the planospiral 

 growth of Spiroloculina. The Sigmoilina growth is much 

 more easily seen in the megalospheric form, the chambers being- 

 fewer and larger. As for the Hauerina plan of growth it is at 

 best only slightly, indicated in my specimens, as in those figured 

 by Millett and Brady, by a slight obliquity of the line of junc- 

 tion of the spiroloculine chambers to the longitudinal 

 axis of the earlier thicker portion of the test. The imperfect 

 state of the Biarritz specimens also does not permit of any 

 -definite verification of the form of the oral aperture. 



This anomalous form may be perhaps with reason trans- 

 ferred to the genus Sigmoilina but I am loth to recommend 

 such a course at present, or until we have a fuller knowledge 

 of the many variations of the milioline plan of growth, and 

 besides, the earlier growth of a shell only shows us the line 

 of departure from type, and the latter points towards the higher 

 or lower type to which the particular form under observation 

 is tending either progressively or retrogressively. In these 

 circumstances I prefer to retain the generic name Hauerina 

 for this species. 



(The specimens are small and poorly developed but appear 

 to be referable to Spiroloculina tateana, Howchin, from the 

 Tertiary of Muddy Creek, Victoria.* Howchin's species is 

 clearly referable to the sub-genus Massilina owing to the pro- 

 nounced milioline arrangement of the early chambers before 



* Trans. R. Soc. S. Austr. vol. xii. 1889, p. 3, pi. I., figs. 4, 5. 



