332 ME. G. MUEEAT AND MISS F. a. WHITTIXG ON 



three times the ordinary diameter immediately below the foramen, bifurcate below, 

 bifurcations slightly swollen iu the middle and each with a small spur near the 

 extremity. (PI. XXXI. fig. 1.) 

 Prom lat. 30 ?f. and long. 40' W. with the other species, and iu lat. 4i'-6° S., long. 

 32' 32' to 30 39' W. It reaches long. 72 W. in lat. 16' to 17° N. 



Amphisolenia inplata, sp. n. Proximal limb composing much the greater part of the 

 body, swollen for half its length to 5 times (lateral view), 2-3 times (foraminal view) 

 immediately below foramen, unbranched, without a spur at the extremity ; distal 

 limb reduced to a fiat membrane ; girdle with each margin expanded into a frill, 

 the distal one wider, the proximal decurrent to foramen. (PL XXXI. figs. 2 a, h.) 

 It occurs in lat. 34° to 39' N., long. 39' to 32' W. 



HiSTiONEis, Stein. 



Owing to our discovery principally of Histioneis Francesc(B and of such other forms 

 near it as S. Farcty it is clear that the distinction between Stein's two genera 

 Histmneis and Ormthocercus disappears. At first we had serious doubts as to the 

 inclusion of O. splemUdus, Schiitt ( = O. splendens^ Schiitt, in Engler and Prantl, Nat. 

 Pflanzenfam. Peridin. p. 29), which appeared to have in place of a sail three spines, 

 somewhat like those of a Ceratoco7*ys. However, on careful examination we found 

 specimens with an extremely fragile sail of much the same character otherwise as that of 

 H. magnifica (see PL XXXII. figs. 1 a, h, c) with similar terminal thickenings. This has 

 escaped attention from two causes : (1) it is frequently broken, and represented only by 

 the three main supports hanging down and giving the appearance of Ceratocorys spines ; 

 and (2) by this species habitually presenting under the microscope its ventral aspect, 

 in which the sail, if present, appears very foreshortened. The distal limb is larger and 

 more arched in H. splendida than in any other Sistio7ieis, and the two plates composing 

 it are joined by a zigzag suture (see PL XXXII. fig. 1 c). Its collar and funnel are 

 alike, and in this important character it is distinct from the other species of Ilistioneis. 

 We suggest the establishment of a section of the genus for the reception of such forms 

 under the name Paraschuettia, which would be not only descriptive (thougli barbarously), 

 but also commemorative of Dr. Schiitt's great services to the study of phyto-plankton. 



H. splendida is a comparatively rare organism in our gatherings, but we found it 

 from lat. 34' 30' X., long. 30' W., to lat. 13° 6' X., long. 78° 44' W. 



B. magnifica (PL XXXII. fig. 2) is one of the most abundant and constantly occurring 

 Peridiniaceae in the warm Atlantic, ranging, according to our records, from lat. 44° N. to 

 lat. 14° 44' S. in the Atlantic an dto Panama in the Caribbean. It varies greatly in size 

 and in the character of the markings on the sail and funnel. We have represented a fairly 

 typical one in fig. 2 for the purpose of comparison with the other species. 



H. remora, Stein, occurred in gatherings from lat. 31° N. to lat. 8 N. in the Atlantic, 

 and to Panama in the Caribbean ; Jff. biremis, Stein, from lat. 31 N. to Panama ; and 

 H. crateriformis, from lat. 31° X., long. 35 W., to lat. 16 N., long. 77' W., i- e. 

 practically the same distribution as the other two. Among the new species which we 



