804 



SYSTEMATIC HISTORY OF THE INFUSORIA. 



Genus TESSELLA (Ehr.). — Frnstiiles broadly tabulate, not concatenate, 

 densely striated longitudinally ; strice alternate, interrupted in the middle ; 

 stipes none ? "It is impossible to judge of the value of the charactei^ that 

 distinguish it from Striatella and Hyalosira whilst we do not know the 

 organic importance or the tnie structiu-e of the striae " (M. I. c. p. 466). 



Tessella interrupta (E.). — Frustules 1 KB. t. 18. f. 4. Mixed with Striatella 

 in front view sulDquadrate. 1-750". | ««?)?w<c^«^«, but less abundant, (viii. 5.) 



Genus HYALOSIRA (K.). — Eilaments stipitate ; frustules quadi^ate, septa 

 alternate, interrupted in the middle, and united by \qyj fine lines. "At 

 first I was afraid that I was led by want of skill in observing, to believe that 

 I could see in the two longer species of this genus a continuation of the \itt3e 

 from one margin to the other, instead of theii^ being interrupted and alternat- 

 ing as they are figured and described by Klitzing. Continuing my observations, 

 I succeeded at last in finding one indi\'idual exhibiting to my sight the alter- 

 nations described ; hence I became convinced that the latter condition is not 

 merely inconstant, but even the least frequent. The secondary suifaces are 

 elHptico-acutc " (M. I, c. 466). 



Hyalosira minntissima (K.). — 

 Shortly stipitate, concatenate ; frustides 

 very minute, partially separating in a 

 zigzag manner. 1-5700". KB. t. 18. 

 f. 3. 2. Mediterranean Sea. 



H. delicatula (K.). — Shortly stipitate, 

 concatenate j frustules minute, quadrate, 

 partially separating in a zigzag manner. 

 1-2640". KB. 1. 18. f. 111. 1. France; 

 Adriatic Sea. (iv. 42.) 



H. rectam/ida (K.). — Shortly stipitate, 

 subcoucateuate, frustides subquadrate, 

 rectauo'ular. 1-1380". KB. 1. 18. f 3. 3. 

 Adriatic Sea (xiv. 23). Frustides larger 

 than in the preceding species. 



H. ohtusanf/ida (K.). — Longly stipi- 

 tate, ribbon-like or subconcatenate; frus- 

 tules quadrate, with obtuse angles. 

 1-1440". Adriatic Sea. (xiv. 29.) Frus- 



tules larger than in the first two species. 



H, punctata (Bailey). — Frustides large, 

 united in long chains, rectangular, sub- 

 quadrate, transversely and uuinter- 

 ruptedl}' vittate, alternate vittie granu- 

 late in the middle of the frustide, the 

 others furnished with a series of con- 

 spicuous pimcta. 1853. Tahiti. 



II. Beswickii (Kormox)., MSS.). — Septa 

 continued across the filament as curved 

 inteiTiipted costje ; valves oblong, with 

 strongly inflated centre and rounded 

 ends ; stride coarse, 30 in -001". New 

 Zealand. On Alg?e from Joseph Bes- 

 ■wdck, Esq. Frustules quadrate ; valves 

 sometimes with siibcapitate apices. [We 

 are indebted to Mr. Norman for the de- 

 scription of this species.] 



Genus RHABDONEMA (K.).— Filaments elongated, shortly stipitate; 

 longitudinal striae uninterrupted, connected by series of transverse striae ; 

 lateral siufaces having transverse striae and a median longitudinal line. From 

 the comparatively large size of the frustules in Rhabdonema, greater facihty 

 is afi'orded for examining their stnicture. The longitudinal striae or ribs 

 (annuli, Sm.) are continuous, parallel, mostly equidistant, and connected by 

 a series of transverse striae, so that, in fact, the structure has a latticed 

 appearance. 



Rhabdonema minutum (K.). — Septa 

 marginal, alternate ; lateral valves ob- 

 long or spindle-shaped, inflated at the 

 middle, transversely striated throughout, 

 SBD. ii. p. 35, pi. 38. f 306. = Tessella 

 Catena, Ralfs, /. c. xii. (not E,). Europe. 

 1- 1200". Smaller than R. arcuatum, from 

 which it differs in the inflated or gibbous 

 centre of its lateral valves, (iv. 41. ) 



R. arcuatum (Lyngb., K.). — Septa 

 marginal, opposite ; lateral valves oblong 

 or linear-elliptic, the transverse striae 

 absent near their ends. SBD. ii. p. 34, 

 pi. 38. f 305. = Striatella arcuata, Ag., 

 E. ; Tessella Catena, E. Common, (x. 

 203, 204.) Differs fi-oni B. minutum 

 in the form of its lateral valves, and by 

 the absence of striae near the end? : tli9 



