OF THE CKYPTOMONADDfA. 



505 



beings 5 and these lie pai'allel to each 

 other. Has the dimensions of P. Uva. 

 Found in decomposing infusions. 

 Schneider describes a peculiar mode 

 of fission seen at times in P. TJvella, in 

 which the segments lie parallel to each 

 other : very probably this supposed spe- 

 cies, P. oceUatum, is nothing more than 

 that pha^e of P. Uvella. The reddish 

 vesicle is worthless as a specific character. 



P. ? virem. — Greenish or actually green, 

 suiToimded by a hyaline cyst. Seen only 

 in process of fission, when each segment 

 had its own filament. These organisms 

 were for some seconds at rest, and soon 

 afterwards moved here and there vdt\\ 

 activity. Very probably this being is 

 only a sporule, and seems nearly akin to 

 CJilamydomonas. 



Genus SPONDYLO^IORUM. — Individuals furnished vdih. a dorsal ocellus, 

 are destitute of a tail, and, in consequence of their imperfect self-division, deve- 

 lope a compound body (polypaiy) resembling a whorl or cluster of berries. 



Spoxdylomoeum quaternarium. — A 

 gi'oup of four alternating coi-puscles, 



of which the tenninal one is the most 



slender ; colour green ; filaments four to 

 five. Length of polyparv 1-576", of each 

 indi^ddual 1-1728". 



FAMILY III.— CRYPTOMONADINA. 



(XYIII. 29-34 ; XIX. 7-16 and 20-31 ; XXVI. 6, 8, 9, 10.) 



The Cryptomonadina {vide General History, p. 140) are Monadina enve- 

 loped within a distinct gelatinous, membranous, or hard induvium, forming a 

 shell-like covering or lorica. According to Ehrenberg, the lorica sometimes 

 resembles an open shield (scutellum), at others a closed box or pitcher (urce- 

 ohis). The constmction of the lorica, however, as a scutellum, open on one 

 side, is denied by every recent writer ; and in all'cases it would appear to 

 completely enclose the contents. Two delicate, filiform, and generally re- 

 tractile filaments, capable of being put into very powerful whirling and lash- 

 ing motion, are clearly perceptible in all the genera, excepting, perhaps, the 

 genus LageneUa ; and even in this. Dr. Wemeck believed he had discerned 

 them. Six or seven species exhibit internal vesicles ; and in two genera a 

 coloured spot is present at the fore part of the body. Prom the position of 

 this speck the dorsal line may be readily conceived, and a right and left side 

 described. Self- division, when it occurs, is simple and complete. " It is 

 possible," says Ehrenberg, " that the fossil animalcules discovered in the flint 

 of chalk and porphyiitic formations, and named by me Pyx'idicida (see Plate 

 XYII. upper figui-es), belong to the genus Trachelomonas.^^ 



Lachmann (oj). cit. p. 219) asserts that in all transparent Monadina and 

 Cryptomonadina a contractile vesicle exists, and that even in the more opake 

 ChUomonas Paramecium and Cryptomonas ovata he was able to observe its 

 contractions. Mr. Carter confiims this statement. 



The genera were thus tabulated by Ehrenberg : — 



Eye-speck 

 absent. 



Eye-speck 

 present. 



( f Form short ; self-division 1 r\ t. 



Lorica obtuse and smooth... ^ l°"^tudinal or wanting Cm>t«mo„a,. 

 I Form lonff and tortuous ; 1 r\ r--j 

 [ self-di4ion transverse | Ophidomonas. 



Lorica pointed anteriorly Prorocentrum. 



Lorica with a neck and narrow orifice Lagenella. 



Lorica with orifice, but no | 



neck. 1 



I I 



Lorica an open sliield 

 {scutellum). 



Lorica a closed box 

 {urccolus). 



Cryptoglena. 

 Trachelomonas. 



