60 BULLETIN 161, UNITED STATES NATIONAL MUSEUM 



in the middle portion, where they are more or less indistinct on account 

 of the thickening of the test, very strongly curved, divided into 

 chamberlets progressively from the peripheral end; sutures distinct, 

 slightly limbate, very strongly curved, sUghtly sigmoid toward the 

 inner end. Diameter, up to 2.5 mm; thickness, 0.45 mm. 



Moebius described this species from shallow-water material from 

 Mauritius, and Egger records it from off West Australia. Most of 

 the material we have can be definitely assigned to this species. 

 Strangely enough all the specimens came from Albatross stations in 

 the deeper water, and no typical specimens were found in the shoal- 

 water material off any of the islands. The species is very distinctive 

 in the considerable thickening of the central portion into a lenticular 

 mass bordered by the thinner flange. 



Genus CYCLOCLYPEUS W. B. Carpenter, 1856 



Cycloclypeus W. B. Carpenter, Philos. Trans., 1856, p. 555. 



Genotype. — By designation, Cycloclypeus carpenteri H. B. Brady. 



Test in the microspheric form Hke Heterostegina in the early stages, 

 later with the chambers becoming annular, divided by radial portions 

 into rectangular chamberlets, the test discoidal and much com- 

 pressed. Miocene to Recent. 



CYCLOCLYPEUS GUEMBELIANUS H. B. Brady 



Plate 18, Figures la, 6 



Cycloclypeus W. B. Carpenter, Philos. Trans., vol. 146, p. 555, pi. 30, figs. 1, 3, 

 1856; Introd. Foram., p. 292, 1862. 



Cycloclypeus guembelianus H. B. Brady, Quart. Journ. Micr. Sci., vol. 21, p. 66, 

 1881; Rep. Voy. Challenger, Zoology, vol. 9, p. 751, pi. Ill, figs. 8a, b (young 

 form), 1884.— CusHMAN, U. S. Nat. Mus. Bull. 100, vol. 4, p. 386, 1921. 



Cycloclypeus carpenteri H. B. Brady, Quart. Journ. Micr. Sci., vol. 21, p. 67, 1881; 

 Rep. Voy. Challenger, Zoology, vol. 9, p. 751, 1884. — Lister, Philos. Trans., 

 vol. 186B, pp. 437, 438, pi. 9, figs. 52-54, 1895.— Chapman, Journ. Linn. 

 Soc. ZooL, vol. 28, p. 22, pi. 2, figs. 6, 7; pi. 3, figs. 1-5, 1900. 



There is a single specimen in the collections from Albatross Station 

 H3876, northwest entrance to Makemo Lagoon, 1 mUe SE., in 

 467 fathoms. 



Family PENEROPLIIDAE 



Subfamily Spirolininae 



Genus PENEROPLIS Montfort. 1808 



Peneroplis Montfort, Conch. Syst., vol. 1, p. 259, 1808. 

 Synonym: Coscinospira Ehrenberg, 1840. 



Genoholotype. — Peneroplis lanatus 'M.ontf ort = Nautilus planatus 

 Fichtel and Moll. 



Test, free, planispiral, close coiled lq the young, usually involute, 

 in the adult becoming variously shaped, close coUed, flaring, annular 



