550 RECORD OF CURRENT RESEARCHES RELATING TO 



portions be made out in the so-called vesicula seminalis, but that the 

 epithelium of the whole glandular tract is of the same character 

 throughout ; this points to the physiological similarity of the secretion, 

 and to the generalization that, howsoever greatly these glands may 

 vary in external characters, they form histologically and physio- 

 logically a single glandular organ, the function of which is the forma- 

 tion of spermatophores. The cause of the variations in form appears 

 likewise to be due to the formation of these bodies. In the female 

 Decapoda the presence of the accessory nidamental glands reveals the 

 existence of two sets of organs. Dr. Brock is of oijiniou that not only 

 is the glandular epithelium of the nidamental gland exactly similar in 

 its primitive condition to the epithelium of the accessory male glands, 

 but that whatever changes do obtain never exceed the limits of indi- 

 vidual modification. When the organ is in function, the epithelium 

 becomes changed in character ; in the male there is the formation of 

 cells in great quantity ; the separate cells are smaller, and vary in 

 form. In the nidamental glands the cells become arranged in two 

 rows, the upper ones ciliated, and the lower developing rod-shaped 

 and regular elements, in the protoplasm of which a number of vacuoles 

 appear. At first sight the diflerences in the water canals which con- 

 nect the genital capsule with the renal sacs are such as to lead to the 

 supposition that they are homologous structures ; but if we consider 

 that the thin pouch of the ovary of the Decapoda only diifers from 

 that of the Octopoda by the absence of a muscular layer, we shall see 

 that the differences between the firm canals of the one and the 

 lacuna-like canal spaces of the other group may be well referred to 

 this cause. In the opinion of the author, what is now seen of the 

 water canals is but the remnant of a more extended system, which he 

 hopes to be able to trace out in the Nautilus. 



Observations on the Organization of Solenopus. * — Solenopus 

 nitidulus was first found by Koren about thirty years since, and 

 subsequently by Professor M. Sars, by both of whom it was considered 

 to be a mollusc, though they were not able to make a thorough 

 examination. Dalyell, however, in the ' Powers of the Creator,' 

 refers it to the Vermes. 



Koren and D. C. Danielssen having obtained numerous specimens 

 of different species, have made more extended investigations into the 

 organization of the animal, of which a brief preliminary description 

 (without figures) appears in the ' Archiv for Mathematik og Natur- 

 videnskab ' of Christiania, 1878. They decidedly confirm the refer- 

 ence of Solenopus to the MoUusca, but as it differs considerably from 

 previously known molluscs, they have not been able to bring it under 

 any of the established orders of Mollusca, although it may well be 

 referred to the great subclass Opisthobranchiata of Milne-Edwards. 

 They have accordingly formed for it a third order of that subclass, 

 which they call Telobranchiata, f because the branchiae are situated 

 at the hinder extremity of the animal. 



The Telobranchiata are naked marine animals, with more or less 



* Translated by W. S. Dallas, in ' Ann. and Mag. Nat. Hist.,' iii. (1879) p. 321 . 

 t From T(?>os, end, and Qpayx^o., giffs. 



