APPENDIX B. 



THE XENOPHYOPHORIDAE, F. E. SCHULTZE. 



THE organisms that are now included in this family were formerly 

 regarded as Porifera, and several of them were described in 1889 by 

 Haeckel in the " Challenger " volume xxiii., on the deep-sea Keratosa. 1 In 

 the year 1892, Goes (1) described "a peculiar arenaceous Foraminifer 

 from the American tropical Pacific" as Neusina agassizii, which Hanitsch 

 in the following year proved to be identical with Haeckel's deep-sea 

 Keratose sponge Stannophyllum zonarium. We are indebted to Schultze 

 (2) for an exhaustive treatise on these genera, and the more definite 

 proof that they are not sponges, but probably related to the Foraminifera. 

 They are spherical or disc-shaped (Psammetta), fan-shaped (Stannojihyllum, 

 Fig. 1), or dendritic (Stannoma) bodies of about 20 mm., more or less, in 



diameter or height, and of a fibrous, spongy 

 texture. They have been found at depths 

 of from 550 fathoms to 3000 fathoms in 

 the Indian, Atlantic, and Pacific Oceans. 



They consist of a plexus of thin-walled 

 tubes, some of which open on the surface, 

 and the meshes of the plexus contain a 

 large number of foreign bodies (xenophya), 

 such as the shells of Radiolaria, Foramin- 

 ifera, spicules of sponges, and grains of sand. 

 The tubes contain either a large number 

 of dark olive-brown bodies, the sterkomata, 

 or else a multinucleated plasmodium con- 

 taining numerous clear solid bodies called 

 the granellae. The sterkomata are remark- 

 ably resistant to strong acids and alkalis, and they often contain fragments 

 of radiolarian and foraminiferan shells. They are regarded by Schultze as 

 of the nature of the faecal balls such 'as are found in other Foraminifera 

 (Gromia, Saccamina, etc.). The tubes containing the sterkomata (Ster- 

 komarium) are probably continuous with the tubes containing the granellae 

 (granella'rium). The granellae are about 1-2 /x in diameter, and are mainly 

 composed of barium sulphate. The nuclei which occur in the plas- 

 modium of the granellariurn are very numerous, and usually scattered 



FIG. i. " 



Stannophyllum zonariiim, Haeck. 

 x . (After Schultze.) 



1 Cf. A Treatise on Zoology, Part II., 1900, p. 154. 

 284 



