422 SUMMARY OF CURRENT RESEARCHES RELATING TO 



segment 13, and thoroforo in front of tbo female generative orifice. 

 There appears to bo but ono pair of spermathcese, which open on to tbo 

 middle of their segment, a little to one side of a seta. The calciferous 

 glands of consecutive segments are not distinct from each other ; they 

 occupy segments 10-14. The gizzard is confined to a single (the 17th) 

 segment. There is a continuous glandular fold on either side of tbo 

 body, which is of the same structure as the clitellum, extending from 

 the 4th to the 24th segment, and interrupting the muscular layers. 

 This glandular mass is specially developed in segment 13, round tbo 

 orifice of the vas deferens. 



Anatomy of Perichseta.* — Mr. F. E. Beddard has some pre- 

 liminary notes on the anatomy of this earthworm. He finds that tbo 

 salivary glands exhibit a metameric arrangement, and be looks upon 

 them as the homologues of the septal glands of the Encbytraeidje and 

 Lurnbricidre. There are a number of small glands which may possibly 

 represent the capsulogenous gland of Lumbricus, but, in the absence of 

 any definite knowledge of the histology of these glands in the earth- 

 worm, it is impossible to speak with certainty. In P. mirabilis and 

 P. aspergillum, the organs consist of groups of unicellular glands. As 

 their number and position differ in four known species, their arrange- 

 ment may furnish a means of discriminating the species of the genus. 



Mucous Gland of Urochseta.t — Mr. F. E. Beddard finds that the 

 " mucous gland " of Urochseta is provided with coelomic apertures, which 

 have the form of large funnel-shaped ciliated discs, composed of the 

 visual columnar cells. This character, added to those discovered and 

 described by Prof. Perrier, completes the resemblance of these organs 

 to nephridia. The " mucous glands " consist, in fact, of a tube opening 

 on to the exterior by a single orifice, and branching distally into a 

 number of tubules, each of which opens into the ccelom by a ciliated 

 funnel. These funnels appear to be disposed irregularly and not 

 metamerically. 



B. Nemathelminthes. 



Structure of Echinorhynchi.J — Br. R. Koebler has had great diffi- 

 culty in obtaining specimens of EcMnorliynclms gigas from the Pig, 

 which seems to be becoming excessively rare. "He was specially inter- 

 ested in the structure of its muscular system. 



He finds that in Echinorhynchi the elements of the muscular system 

 become differentiated into cells ; these are sometimes numerous, and the 

 contractile substance forms a single group of fibrils in each cell (trans- 

 verse fibres of E. heruca) ; sometimes the fibrils form two or three 

 distinct groups in each cell, but the size of the latter does not notably 

 increase, nor does the protoplasm become less abundant (longitudinal 

 fibres of E. heruca). In other forms (E. angustatus and E. proteus~) the 

 groups of fibrils become more numerous in each of the muscular cells, 

 and these are larger in size, and the remains of the protoplasm are more 

 reduced. Finally, in E. gigas, the muscular cells are of enormous 

 size ; a very large number of fibrils appear in their protoplasm, and take 

 on a much more complicated structure than in other types ; they become 

 much more perfectly isolated, and are better differentiated from the 

 formative protoplasm in which they are placed. 



* Zool. Aazeig., xi. (188S) pp. 91-4. f Ibid., pp. 90-1. 



% Jcmrn. Anat. ct Physiol. (Robin), xxiii. (1887) pp. 612-59 (2 pis.). 



