OF THE TRACHELINA. 617 



tremulous flap to the mouth, and in Chilodon and Nassula a cylinder of rod- 

 like teeth, which sometimes projects in advance of the mouth. Bursaria and 

 Rassida have a thick frontal protuberance. The reception and discharge of 

 coloured matter can be seen in all the genera. In Nassula the violet- coloured 

 specks (bUe) are worthy of notice. In Spirostomum the mouth is spiral. A 

 nucleus and one or more contractile vesicles occur in all the genera. Com- 

 plete transverse and longitudinal self-division is frequent and complete. 



The genera are disposed as follows : — 



( ( ^'Oi f '^^th a nip long, proboscis-Uke Trachelius. 



Brow con- 

 No tremu- tinuoua 

 lous J with the"* 



, mouth- I body. 



brow-hke \ 

 ■53 \ upper Up [ Hp broad, hatchet-shaped. . .Loxodes. 



o 1, brow-hke prominent back Bursaria. 





i^ Mouth spiral Spirostomi 



^ Brow interrupted in a peg-like manner Phialina. 



\^ Mouth having a tremulous flap Glaucoma. 



A brow-like prominent upper lip Cliilodon. 



A brow-like prominent back Nassida. 



This family is not recognized by Dujardin, who rejects the supposed affini- 

 ties of its genera as imnatural ; and indeed it must be owned that the Tra- 

 chelina, as understood by Ehrenberg, represent a heterogeneous collection 

 rather than a natural group. Bursaria includes some mouthless Opalinm. 

 Spirostomum evidently takes its place next to Stentor ; and Chilodon and 

 Nassida are removed in several important details of organization fi'om Tra- 

 chelius and Phialina. 



Perty retains in his classification a family Trachelina, and places in it the 

 genera Trachelius, Harmed irus,Amphileptus, Loxophyllum, Dileptus, Pelecida, 

 and Loxodes, — adopting, however, the characters assigned by Dujardin in 

 preference to those given by Ehrenberg. The brief character of Trachelina 

 recorded is — " Body elongated anteriorly into a neck-like process, or pro- 

 truding a proboscis curved on one side." 



We have retained in the preceding description of Trachelina, adopted fi'om 

 Ehrenberg, several notes of stnictm-al peculiarities which subsequent re- 

 searches show to be erroneous. That the mouth is lateral and the anus ter- 

 minal in all the members of the family is not the case. Thus, in Chilodon the 

 discharging orifice is on one side, near the posterior extremity. Lachmann 

 {A. N. H. 1857, xix. p. 216) speaks of the buccal orifice of Glaucoma as 

 produced into two fiaps. The teeth (so called) in Nassula, Chilodon, kc, 

 have no real claim to that designation ; for they are no more than folds or 

 thickenings of the oesophagus (see Part I. p. 311). The violet- colom-ed spots, 

 imagined by Ehrenberg to be vesicles, are merely accidental specks of colour 

 derived from the food (see p. 312, and notes on Nassula elegans). 



Chilodon and Nassula have been proved to propagate by living embiyos, 

 after a previous encysting-stage ; and in all probability most of the other 

 genera do so likew^ise. Nassula ambigua (Stein) has been seen in the same 

 encysted condition as Chilodon ; and only the last stage, that of the internal 

 development of a ciliated embryo, to complete the cycle as in Chilodon, has 

 escaped observation. 



