Miscellaneous. 323 



this Perichceta is very widely spread, its resemblance to the true 

 Lumbrici alone causing it not to be recognized. 



According to my observations this worm, whilst seeking moisture 

 and warmth, delights in light and aerated soils. Under conditions 

 of captivity in wliich the earthworms easily live, P. diff ring ens does 

 not thrive well ; in damp moss it survives for a considerable time, 

 but in a wet clay or marly clay soil it dies in a few days. When 

 placed in water, suffocation takes place comparatively quickly. 

 When this annelid is dead the middle part of its body is already 

 decomposed, whilst the two extremities, having retained their normal 

 appearance, are still capable of contracting under the influence of 

 excitants. In Lumbricus terrestris, as is well known, decomposition 

 under these circumstances advances with more regularity from 

 behind forwards. When irritated, the animal, like various Lum- 

 brici, emits from its dorsal perforations a greenish-yellow liquid, 

 full of Psorospermia), measuring 0-026 by 0-018 millim., and having 

 very granular contents. 



Anatomically P. diffriiigens differs but little from P. cingidata and 

 posthuma, which I described in 1867. The nervous system is con- 

 structed on the same plan. Behind the testes, in the midst of the 

 great dorso-ventral vascular trunks, I have found lateral, pyriform, 

 ganglionic inflations, measuring 0*128 by 0-092 milKm., situated 

 upon the course of the nerves, which recalls to mind an arrangement 

 well known in some Hirudinece. The nerves which spring from 

 the connectives uniting the ventral ganglia are very distinct, as in 

 Lumbricus. In the last four or five segments the ganglia become 

 less distinct, and the two lateral halves of the apparatus tend to 

 separate. 



The gizzard presents interiorly a translucent chitinous apparatus, 

 of an opaline white colour, with iridescent reflections, forming a 

 section of an hexagonal pyramid, nearly 4 millims. in height ; and this 

 apparatus, singularly enough, does not adhere to the waU of the 

 digestive canal, a fact which in my previous researches I beKeved 

 (but, as it seems, wrongly) was to be ascribed to the state of 

 preservation of the individuals submitted to my examination. 

 The intestinal part of the digestive cavity, less simple than in 

 Lumbricus terrestris, varies in colour in the course of its passage ; 

 and in this respect we may distinguish in it three portions : the 

 first, extending to the lateral caeca, already well known in P. cin- 

 gidata, is reddish, as are also these ca3ca at their adherent portion ; 

 the second and the bottom of the cajca are yellowish ; and the third 

 portion, wliich is less inflated than the preceding, is brownish red. 

 The dissepiments which sustain this last appear more distinct. 



In this species I have not met with the large gland which, in tho 

 species previously studied, unites by its duct with the deferent 

 duct towards its opening ; on the other hand, the latter, which is 

 0-08 miUim. in width during its course, becomes inflated into a 

 club at its termination, where its diameter attains 0*48 millim. 

 This dilated portion is recurved in the form of an S ; the waU, which 

 is very thick, seems to contain some glandular cells, but is chiefly 



