724 MESSES. E. HERON-ALLEN AND A. EAELAND ON THE 



attached to a large smooth surface such as a rock or a molluscan shell, where it has 

 free scope for development and full access to the surrounding medium, will preserve a 

 depressed and scale-like form which may attain the enormous dimensions of those 

 described by Miss Lindsey under the specific name of G. plana (Carter), 3-4 inches in 

 diameter (Trans. Linn. Soc. London, Zoology, ser. 2, vol. xvi. pp. 45 et seq.), whereas 

 an individual of the same stock confined to a cranny or confined space of any kind 

 tends to form a solid mass of superimposed chambers. The resulting organisms are 

 quite different in external appearance. We have no doubt whatever that the whole 

 series of specimens which we have for purposes of identification listed under the 

 following varietal names are no more than normal G. inhcerens subjected to differing 

 environmental conditions. 



430. G-ypsina inli^rens (Schultze). 



Acervulina inhcerens Schultze, 1854, OP. p. 68, pi. vi. fig. 12. 

 Tinoporus lucidus Tervigi, 1880, SGl^. p. 213, pi. iv. fig. 70. 

 Gypsina inhcerens Brady, 188-t, FC. p. 718, pi. cii. figs. 1-6. 

 Goes, 1894, ASF. p. 91, pi. xv. fig. 787. 

 Millett, 1898, etc., FM. 1904, p. 599. 

 „ „ Chapman, 1900, FLF. p. 198. 



„ „ Rhurabler, 1906, FLC. p. 72, pi. v. fig. 60. 



„ „ Chapman, 1907, RFV. p. 140. 



16 Stations. 



Occurs almost universally and is often one of the most abundant species in the 

 coarse siftings. The specimens exhibit the widest possible variety, ranging from 

 fragments of what must have been enormous specimens of the large-chambered and 

 coarsely areolated type G. -plana (Carter) to thin encrusting layers often only a single 

 cell thick, and nearly circular ^in outline, separable with difficulty from Planorhulina 

 mediterranensis d'Orbigny, the rotaliform early chambers being distinctly visible on the 

 inferior surface of the shell. Other specimens were found, especially at Stns. 2, 3, 4, 

 6, 10, and 12, in which the test was flat and roughly circular in outline, but with 

 a secondary series of chambers piled over the central portion in acervuline fashion, 

 rendering them hardly distinguishable from Planorhulina larvata Parker & Jones. 

 At Stns. 3 and 5, the species was found encrusting calcareous algas so as to form 

 cylindrical masses. The presence of definite arched apertures at the side of each 

 chamber, Avhich has been regarded as a distinguishing feature of Planorbulina as 

 contrasted with Gypsina, is not in all cases reliable. We have unquestionable 

 examples of G. inhcerens possessing normal planorbuline apertures to some of the 

 marginal chambers and not to others. Chapman, in recording this species from 

 the Cocos Keeling Atoll (C. 1902, CKA. p. 232), calls attention to the deep rose- 

 colour of his specimens, a feature vi^hich we have discussed elsewhere {post, no. 432). 



