314 
THE VOYAGE OF H.M.S. CHALLENGER. 
In deep-water gatherings rich in arenaceous Foraminifera there often occur, associated 
with Hap lophragmium globiger ini forme or with Verneuilina propinqua, as the case may- 
be, irregular specimens presenting intermediate characters, the earlier growth of which 
is frequently bi- or tri- serial as in some of the Textularince, whilst the later chambers 
are much inflated, and are arranged more or less on the Rotalian plan. The tests are 
coarsely arenaceous, and generally of dark-brown colour. The drawings (figs. 12-15) 
give a fair idea of the forms such specimens assume. They are too frequent to be 
regarded as mere monstrosities ; and as they mark an interesting morphological 
condition, it appears desirable that they should have a distinctive name. 
This variety has been collected as far north as the entrance to Davis Strait, 1750 
fathoms (Norman) ; at Station 24, off Culebra Island, 390 fathoms ; at Stations 323 and 
332, off the coast of South America, 1900 fathoms and 2200 fathoms respectively ; and 
at Station 299, between Valparaiso and Juan Fernandez, 2160 fathoms. It also occurs 
in some of the “ Porcupine ” dredgings from the North Atlantic. 
Placopsilina, d’Orbigny. 
Serpula, pars, Schroeter [1784], Linne. 
Placopsilina, d’Orbigny [1850], Reuss, Parker and Jones, Carpenter, Terquem, Brady. 
Lituola, pars, Jones and Parker [1860], Carpenter, Brady, M. Sars. 
Test adherent, arenaceous, rough externally ; with one or many chambers, of which 
the cavities are simple and undivided. 
The description of the genus Placopsilina originally furnished by d’Orbigny, is 
contained in a brief note in the Prodrome de Paleontologie stratigraphique, vol. ii, 
p. 96, and is couched in the following terms : — “ Ce genre ressemble aux Truncatulina, 
mais est tonjours fixe, et n’a d’ouverture qu’ a la partie superieure de la derniere loge.” 
Nothing is said of the composite or arenaceous structure of the test, but the reference at 
a subsequent page to one of the figures in Cornuel’s memoir on Lower Cretaceous 
microzoa sufficiently indicates the group of organisms which the author had in view ; and 
the name has been accepted by Reuss, Carpenter, Terquem, and others, in the sense in 
which it is employed in the present Report. 
Some confusion has not unnaturally resulted from the analogous habit of growth 
presented by this genus and the isomorphous section of the Trochamminince ; but 
amongst recent specimens the rough exterior of the test in Placopsilina is readily dis- 
tinguished from the finely cemented, richly coloured, and often polished surface of 
the investment of Webbina. 
The genus Placopsilina makes its appearance at the beginning of the Liassic period, 
