5S8 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and regftrds both tlic structures above mentioned as homologous with the 

 latiral organs of Nemcrteans. The similarity in development is un- 

 doubtedly very striking, and according to Salensky warrants us in 

 associating the three eventually very ditlbrent organs in a morphological 

 Series. 



Bilharzia.* — Herr G. Fritsch has reinvestigated the anatomy of 

 H'dhnrzhi lisematuhia Cobbold. In the introductory chapters the occurrence 

 and distribution of this important jiarasite, its jirobably almost un- 

 exceptional origin from impure water, its various names, and the curious 

 copnlatory conditions arc discussed. 



The author then gives a detailed account of the structure of tho 

 female, of which we have hitherto been to a great extent in ignorance. 

 The skin is not smooth, but covered with minute, scattered, readily 

 broken spines. They are directed forwards, and perhaps hinder tho 

 animal from slipping out of tho canalis gynaecophorus. Tho mouth, 

 pliarynx, and divided limbs of the alimentary canal are then noticed. 

 Tlie vagina leads to tlie expanded uterus, and a narrowed portion of tho 

 latter ought to be called the oviduct. He identifies as the shell-gland 

 what Bilharz called the " capsule," and treats of tho unpaired ovary, tho 

 largo vitelline organs, the hitherto imdescribed excretory apparatus, 

 and the distinct caudal excretory pore. The next chai)ter describes tho 

 position of the above organs in cross sections. The author then dis- 

 cusses the histological details : — the clear refrcctive cuticle without 

 distinct subcuticular layer, the incons2)icuousness of distinct skin-glands, 

 the sparse longitudinal muscular fibres, and the absence of any closed 

 circular sheath, the connective tissue of the parenchyma, and the like. 

 The histology of the reproductive organs is described in detail. No 

 Laurer-Stieda canal was to be found. As was to be expected, very little 

 of the nervous system could be made out. 



The structure of the male is very simple. The formation of tho 

 gynnscophoric canal, tho suckers stronger than those of the female, tho 

 slight development of the alimentary canal, the union of the two limbs 

 as in the female behind the generative gland, the position of the testis 

 very near the ventral sucker, the opening of the vas deferens in tho 

 depth of the first part of the canalis gynsecopliorus, the absence of any 

 copulating organs, are described at length. Finally, the histology is 

 briefly reviewed. The strong cuticle with its fine spines, the longi- 

 tudinal muscles, the practical absence of glands, the muscular pharynx, 

 tho muscular seminal vesicle without distinct epithelium, but with 

 peculiar cuticular insheathing, the central nervous system more distinct 

 than in the female, are shortly described. 



5. Incertae Sedis. 



Balanoglossus Mereschkovskii.t — Herr W. Schimkcwitsch gives an 

 account of this northern species of Balanoglossus. The body may be 

 divided into three parts : cephalic lobes, a single body-segment, and a 

 hinder unsegraented portion ; it may be compared with a larval Ascidian, 

 save that the latter has no cephalic lobes. The unpaired head-ccelom 

 opens to the exterior by means of a left excretory canal only ; the latter 

 exhibits the same relation to the peritoneum of the ccelom as do tho 



* Arch. f. Mikr. Anat., xxxi. (188S) pp. 192-223 2 pis.), 

 t Zool. Auzcijj., xi. (1888) pp. 280-3. 



