278 HENRY B. BRADY. 



the shell-wall of which, especially in the young condition, is 

 delicately thin and transparent, and conspicuously perforated. 

 But for these characters, such forms as that now described 

 under the name Sp. ijicequalis might easily be mistaken for 

 minute adherent annelids. 



Several well-marked modifications of the genus, which 

 have hitherto escaped the notice of naturalists, have been 

 found amongst the minuter Foraminifera of shallow water, 

 especially of tropical seas, and some of these have been 

 selected for description. The enumeration of their dis- 

 tinguishing zoological characters with the drawings figs. 25 

 to 28 of Plate VIII, will be sufficient to shov/ the lines in 

 which they diverge from the few already known species. 



Spirillina in^qualis, n. sj). PI. VIII, fig. 25, a, b. 



Characters. — Test free or adherent, discoidal, thick ; in- 

 ferior face flat, broader than the superior j superior surface 

 excavated at the umbilicus. Composed of anuraber of convo- 

 lutions (three to five) of a non-septate tube. Inferior peripheral 

 margin acute or sub-carinate, superior obtuse. Shell- 

 wall conspicuously foraminated. Diameter, y?^ inch (0"o6 

 millim.). 



Compared with the typical .Spirillina vivipara, this species 

 presents a small thick shell, with a sloping instead of a 

 rounded peripheral wall. Though it has never been met 

 with attached to any hard body, the appearance of its in- 

 ferior surface and the fact of its being brought up upon 

 miuute shreds of alga? and the like, leave little doubt that it 

 is of parasitic habit. The extension of the margin of the 

 inferior surface is due mainly to the thickening of the shell- 

 wall, which on the superior side remains thin, perforate, and 

 delicately transparent. 



Spirillina incequalis has been found in several localities, 

 notably off Nightingale Island (100 to 150 fathoms), off 

 Honolulu Reefs (40 fathoms), and from the Admiralty 

 Islands (17 fathoms). 



Spirillina limbata, n. sp. PI. VIII, fig. 26, a, h. 



Cliaracters. — Test planospiral, thin, equilateral, discoidal ; 

 peripheral margin square. Spiral sutural line marked ex- 

 ternally by a raised band of shelly deposit; surface other- 

 wise smooth. Diameter, ^V i"ch (0-4 millim.) 



This is a well-marked form differing from Sp, vivipara in 



