Naviculacea.l infusorial animalcules. 385 



Haxionyx senarius. — Surface of testiileswith six rays, their intervals 

 occupied by parallel lines ; transversely and loosely cellular, umbilicus 

 entire, dotted. Diameter 1- 720th. Southern Ocean j approaches 

 Actinocyclus hiternarms. 



H. duodcnarins. — Kays twelve ; umbilicus large, with no dotted 

 rays. Diameter 1 -576th. 



Genus HELiorKLXA, (Ekr.) — Lorica of two equal valves, orbicular, 

 not concatenated (?); divided intcniaUy into cells by imperfect 

 radiating septa, which alternate with a series of external depressions ; 

 centre smooth, angular, with large marginal apertui-es, equal in num- 

 ber to the rays ; and with closely-set, erect spines, beneath the 

 margin, on each side. The surface of the valves appeal's as if over- 

 spread with a line granular membrane, or veil. 



Has the habit of Actinoptychus, but differs, like Benticella, from 

 Biddulphia, by the lateral spines of the margin connecting the lorica 

 in pairs, when young 



H. Iletii. — Testules with six rays and septa, with three radiating, 

 loosely cellidar, elevated area?, alternating with a like number of 

 depressions, ornamented by decussating fine lines; margin (rim) 

 ■wide, radiate ; one or three marginal spines to each cellular space, 

 and two to fom- to the otMr ai-eee ; umbilicus stellate, smooth ; 

 angles not prominent. Diameter 1-S72nd. Bermuda. Fossil. Has 

 the habit of Actinoptijclius velatus. 



H. Leeuwenhoekii. — Eight septa and rays ; cellular areoe four, and 

 as many alternating lined spaces ; rim wdde, radiate ; marginal spines 

 four to the areae of each kind ; umbilical star smooth, tetragonal 

 (P. 14, f. 35.) Diameter l-204th. Bermuda; discovered by 

 Dr. Bailey. 



H. Euleri. — Ten rays and septa, with five radiating area) of each 

 sort ; margin with spines alike in the two ; umbilical star pentagonal, 

 smooth. Diameter 1-1 56th. Bermuda. 



H. Selligucii. — Twelve radiant septa, and six radiating and alter- 

 nating spaces of the two kinds, spines equal and alike in the two ; 

 umbilical star smooth, hexagonal. Diameter l-156th. Bermuda. 



Genus Hemiaulus. — Lorica bivalve, compressed, subquadrate, 

 fission perfect, hence not concatenate. Two tubular processes situated 

 on each side ; those of one side closed, of the other open ; no con- 

 strictions on the sides. 



