FOEAMINIFERA OF THE ATLANTIC OCEAN, 61 



TECHNITELLA THOMPSONI Heron-Allen and Earland. 



Plate 24, figs. 1, 2. 



Technitella thompsoni Heron-Allen and Earland, Jouin. Quekett Micr. Club, 

 eer. 2, vol. 10, 1909, p. 403, pis. 31, 32, 34, fig. 8. 



This species is described as follows : 



Test free, subcylindrical, rounded and slightly tapering at one extremity 

 and bluntly truncate at the other, consi.sting of a hollow chamber with composite 

 walls built up entirely of echinoderm plates in a more or less perfect condi- 

 tion. The plates which overlap each other are fastened together without visible 

 cement. No special aperture at either end of the test, the extremities being closed 

 by means of similar plates set at an angle so that they resemble the incurving petals 

 of a flower. Surface of the test neat and regular, and entirely devoid of extraneous 

 matter, but the projecting edges of the flat (or slightly curved) plates used in the 

 construction of the tost give a somewhat irregular or serrate appearance to the outline. 

 Hyaline-white in appearance, with slight ii-idescence when dry, due apparently to 

 diffraction effects caused by the film of chitin with which the separate plates are 

 probably fastened together. 



Length, 1.8 mm.; breadth at truncate extremity, 0.350 mm., widening to 0.4 mm., 

 and again diminishing somewhat rapidly to 0.250 mm. at the tapering extremity. 



Distribution. — Tiiis very interesting species was first obtained by 

 the Goldseeker in Moray Firth in 33 fathoms (station 8, 57° 55' N.; 

 3° 20' Wj, and another specimen was later obtained in the North 

 Sea in 39.71 fathoms (station 4lC, 56° 35' N.; 0° 10' W.). 



The selective power of this species in choosing only the plates of 

 echinoderms from the mass of the bottom material is very interesting. 

 As the selective power is so striking, some of the notes of the authors 

 are here given : 



As illustrating the skill of Technitella thompsoni and the great selective power exhib- 

 ited by the animal, it may be stated tliat in neither of the dredgings in which it has 

 been found do echinoderm plates, such as are used in its construction, abound. They 

 occur in considerable numbers, a.s always is the case of shallow-water dredgings, but 

 they form an infinitesimal percentage of the material as dredged, and their presence 

 would be almost unobserved unless especially searched for. 



Genus WEBBINELLA Rhumbler, 1903. 



Webbina Jones, Parker, and H. B. Brady (type, Webhinu hemisphaerica Jones, 

 Parker, and H. B. Brady), Pal. Soc. Mon., 1865, p. 27 (not Webbina d'Orhigny, 

 1839).— H. B. Brady (part). Rep. Voy. Challenger, Zoology, vol. 9, 1884, 

 p. 34S.— Chapman, Ann. Uag. Nat. Hist., ser. 6, vol. 18, 1896, p. 326. 



Psa/nmosphaera Eimer and Fickert (part), Zeitschr. Wiss. Zool., vol. 65, 1899, 

 p. 671. 



Webbinellu Rhu.vibler (part), Arch. Prot., vol. 3, 1903, p. 228. — Cushman, Bull. 

 71, U. S. Nat. Mus., pt. I, 1910, p. 50. 



Description. — Test fixed, circular in outline, the central portion 

 convex, the peripheral portion often forming a flattened flangelike 

 rim about the central portion; chamber single, undivided, wall of 

 medium thickness, composed of fine sand grains with a large propor- 

 tion of cement rather sraootlily finished both without and within; 



