RHABDAMMININAE 33S 



80. Rhabdammina discreta, Brady. 



RliabdopUura sp. Dawson, 1870-1, G. St L., p. 177, text-fig. 7. 



Rliabda?ii)iiiiia discreta, Brady, 1879, etc., RRC, i88i,p.48; 1884, FC, p. 268, pi. xxii, figs. 7-10. 



Rhabdammina discreta, Cushman, 1918, etc., FAO, 1918, p. 21, pi. xi, fig. i. 



One station: WS 225. 



Not uncommon, the specimens rather small. Fragments, probably referable to this 



species but not in a condition to be determined with certainty, occur at WS 96 and 210. 



Genus Protobotellina, Heron-Allen and Earland, 1929 



81. Protobotellina cylindrica, Heron-Allen and Earland (Plate XVH, figs. 9-13). 

 Protobotellina cylindrica, Heron-Allen and Earland, 1929, etc., FSA, 1929, p. 326, pi. ii, figs. 

 9-13- 



Eight stations: WS 77, So, 109, 213, 215, 229, 231, 243. 



Test large, irregularly cylindrical, in the form of an unseptate tube with walls of even 

 thickness, open at one extremity, closed at the other. Colour, dark grey to pale brown. 

 The aboral extremity is abruptly truncated and exhibits no sign of a bulbous proloculum 

 either externally or in section. The oral extremity is generally rounded off, but sometimes 

 rather flattened and outspreading, and is furnished with a round or oval constricted 

 aperture, which is reduced in size or defended by spicules, or larger sand grains pro- 

 jecting from the inner wall. 



The wall is thick and built of fine sand grains and broken sponge spicules firmly 

 agglutinated, but with little visible cement. The proportions of sand and spicules vary 

 greatly ; in some specimens the spicules predominate. The external surface is smooth and 

 neatly finished. Feeble constrictions and swellings, visible externally, give an impression 

 of internal septa which do not in fact exist. The central tube is unseptate and approxi- 

 mately of the same diameter throughout. Sections occasionally show a constriction of 

 the inner tube due to a thickening of the wall, but these cannot be regarded as primitive 

 or degenerate septa, nor do they coincide with the constrictions of the outer wall. In 

 diameter the tube is about equal to the thickness of its surrounding wall. 



The inner surface of the tube is extremely rough, owing to the projection of spicules 

 and sand grains larger than those employed in the construction of the outer wall. These 

 spicules and sand grains frequently project almost to the middle of the tube, but never 

 across it, nor do they form a labyrinthic structure in the tube, as in Boiellina labyrinthica. 

 The entire tube is filled with a homogeneous mass of protoplasm, nearly black in colour. 



The spicules and sand grains projecting from the inner wall are presumably so placed to 

 exclude parasitic worms. These are a source of trouble to most large Foraminifera, and 

 many devices are employed for their exclusion . That it is not entirely effective is proved by 

 our finding a Sipunculid inside a large specimen. Whether such organisms resort to 

 the tubes for food, or for shelter only we cannot say. They are not tube builders. 



Externally Protobotellina bears considerable superficial resemblance to Botellina 

 labyrinthica, Brady, but a close examination reveals generic differences. The fine sand 

 and spicules, although firmly built into the wall of Protobotellina, can be scraped away 



