36 



BULLETIN 104, UNITED STATES NATIONAL MUSEUM. 



Distribution. —Thin species has not been distinguished often from 

 the related species P. fusca. Flint described it from the coast of 

 Brazil, Albatross D2760 in 1,019 fathoms. Heron- Allen and Ear- 

 land record it off the Hebrides. 



It is evidently a distinct species from P. fusca and the habit of 

 ])uilding a large sponge spicule into the test appears distinctive. 

 The following notes from Heron-Allen and Earland ' are of interest 

 in this connection: 



111 * * * parva, the test, which is always of comparatively small dimensions, is 

 nearly symmetrical and spherical, composed of small sand grains rigidly cemented 

 together, wdthout definite aperture of any kind and very often around a sponge spicule 

 which projects on opposite sides of the sphere, sometimes to a length many times ex- 

 ceeding the total diameter of the test. * * * This spicular form is of very infrequent 

 occurrence, and is in our experience extremely local. [In their paper, they have P. 

 fusca from 85 out of 145 stations examined and spiculiferous var . parva occurs at but two 

 stations, and at only one of these was more than an occasional specimen found.] The 

 one exception is haul 228, taken off St. Kilda west of the Hebrides in 1,600 meters, the 

 sea bottom being Globigerina ooze. Here the spiculiferous variety parva is of quite 

 frequent occurrence. In view of such facts, and of the added fact that two species 

 of Fsammosphaera, which we have described from Goldseeker's dredgings [P. how- 

 inanni, mica plates, and P. rustica, sponge spicules] display marked selective powers, 

 we can not but arrive at the conclusions that the presence of this central spicule in 

 A^ar. parva is not fortuitous, but that the animal deliberately chooses the spicule as a 

 main constituent of its "house, " and constructs its abode round the spicule in order 

 to obtain the increased support afforded by its projections in supporting itself upon 

 the surface layers of the bottom ooze. 



I have had specimens from the following list of stations : 



Psammosphaera parva — material examined. 



PSAMMOSPHAERA BOWMANNI Heron-Allen and Karland. 



Plate 9, figs. 5, 6; plate 10, fig. 5. 



Psammosphaera boivmanni Heron-Allen and Earland, Journ. Roy. Micr. 

 See, 1912, p. 385, pi. 5, figs. 5, 6; pi. 6, fig. 5; Proc. Roy. Irish Acad., vol. 31, 

 pt. 64, 1913, p. 39; Trans. Linn. Soc. London, vol. 11, pt. 13. 1916. p. 219. 



The following is from the original description: 



Test free, monothalamous, consisting of a more or less irregularly polyhedral 

 chamber, constructed of small flakes of mica cemented together at the edges by 

 a light-gray mudlike cement. Xo definite oval aperture. There is often a small 

 opening where two or three of the mica flakes meet at an acute angle, due to 



1 Jonm. Rov. Micr. Soc, 1913, p. 17. 



