32 SUMMARY OF CURRENT RESEARCHES RELATING TO 



importance that the primary nerves are accompanied by a layer of 

 nerve-cells.* 



The digestive system is divisible into a muscular buccal mass, a 

 ciliated intestine and the rectum ; the pharynx possesses a number of 

 radial folds, and there is an inner coating of a yellowish chitinous 

 cuticle. No trace of a radula is to be seen in Neomenia, but in Proneo- 

 menia it is interesting to observe a muscular process representing the 

 tongue and invested in chitin ; salivary glands ajipear to be present. 

 The intestine is uniform throughout, with thin walls, j^rovided 

 anteriorly with a ctecum ; the lumen is obstructed by the deep trans- 

 verse folds, found in this form and its allies, and there are indica- 

 tions of an iucompletely differentiated liver, in the form of secreting 

 cells on the lateral portions of these laminae. 



The generative system is perfectly symmetrical, and consists of the 

 germ-gland, which is situated along the whole length of the body, 

 and is dorsal, and of the different cavities and canals found at the 

 hinder end of the body. The ger.eral type in the Solenogastres 

 ajDpears to be the possession of a double genital gland which com- 

 municates with the pericardium ; from this a comj^lex of ciliated and 

 glandular ducts leads towards the exterior, to which it opens in the 

 region of the anus. The author thinks it possible that part of the 

 conducting tubes of the genital system represent the kidney. If this 

 view is supported, we shall find in Neomenia a form in which 

 the genital products are discharged by a pair of ducts into the 

 body-cavity (pericardium) ; thence they are conducted by paired 

 ciliated ducts into the cavity of the kidney; in other words, we 

 have indications of a more primitive stage in which the cavity of the 

 pericardium was the meeting-point of the efferent ducts of the genital 

 glands, and the excretory ducts of the renal organ. 



The circulatory system is almost completely lacunar, the heart is 

 more or less saccular in form, and as radiating fil)res traverse its 

 cavity, it has a resemblance to the embryonic heart of some higher 

 Gastropods : it is possible that the blood-corpuscles contain hsemo- 

 globin. There appear to be no branchife at the posterior extremity 

 of the body. The paper concludes with a detailed comparison of this 

 form with Neomenia and Chcetoderma ; and of the Solenogastres 

 generally with the other division of the Amphineura — the Polypla- 

 cophora. 



Molluscoida. 



Development of Salpa.f — Professor W. Salensky has a preliminary 

 communication on this subject, to which his attention has been 

 compelled by the different results obtained by Brooks and Todaro, 

 as compared with those of his own earlier investigations. He now 

 finds that there are great differences between the S. democratica which 

 he previously examined, and the S. pinnata, which was the subject of 

 Todaro's studies. In all species of Salpa the ovary is found at the 

 hinder end of the body, and consists of an egg-cell, enclosed in a 



* We may observe that Balfour has noted a number of commissures between 

 \he ganglia, and a ventral ganglioniQ layer in the ventral cords of Peripatus, 

 t Zool. Anzeig., iv. (1881) pp. 597-603, 613-19. 



