Royal Microscopical Society. 203 



top in Islington, while moss on a garden wall at Battersea has 

 furnished C. bidens, but no C. vaga. 



With the exception of the strange head, and the gliding crawl 

 necessitated by the arrangements of its parts, there is no great 

 peculiarity to distinguish this from most other philodines ; it has, 

 like them, two lobes, but these — although separated by a clear 

 unciliated space — are not split up into two independent rotatory 

 organs inclined laterally right and left when in action, and slightly 

 over to the dorsum, but are generally kept down nearly in the 

 same plane as the ventral surface on which the creature swiftly 

 crawls, while the cilia brush over the path traversed and sweep all 

 loose matter, including food, towards the buccal cavity ; — not 

 directly into it, however, but sufficiently near, on each side, to 

 permit the sucking action of its ciliary current to have full play on 

 the passing atoms. 



Kunning at the back, or unciliated portion of the confluent 

 lobes, we have the representative of the ordinary proboscis : in this 

 case soldered to, and having no action apart from, these lobes : it is 

 furnished with a permanent frontal hook, only seen as such in a 

 side view (Fig. 2). Unintentionally I may be straining analogy 

 too far in considering this a proboscis ; except in bearing the un- 

 usually well-developed hook, it is not at all like the ordinary 

 proboscis : but it is somewhat remarkable that occasionally a philo- 

 dine may be seen crawling with half retracted rotatory organs and 

 proboscis arched over them, affording most perfect resemblance to 

 C. vaga ; for the ciliary frills in this rare case are drawn together 

 into a thick brush, sweeping the way, while at the back of these, in 

 close contact, comes the extended proboscis, with its soft anterior 

 finger or hook. Is it too fanciful to think that the head of C. vaga 

 may be a permanent form of an exceptional and transient figure 

 assumed by that of other philodines ? 



Each clump of cilia, or lobe, is bounded at the neck by a strong 

 process — perhaps the homologue of the trochal pedicle in Kotifer, 

 &c, — rigid, except at its base, and deeply serrated at the free 

 curved ends, which appear to come level with the tips of the cilia 

 (Fig. 1). Between these comes the capacious oral aperture with its 

 strong ciliatory current, inwards or outwards, apparently as the 

 creature wills. 



The oesophageal tube as usual goes direct to the mastax, and 

 this delivers the masticated prey to a slightly convoluted central 

 duct of a large cylindrical stomach. Beyond, and, I think, divided 

 by a valve, comes a small spherical intestine, with a short, com- 

 monly closed, passage round the contractile vesicle to the anus. 

 In fully grown specimens the period of the contractile vesicle aver- 

 ages two minutes, but it evidently grows slower with age ; thus, 

 when the animals are very small and young, the sac fills and 



Q 2 



