192 bulletin: museum of comparative zoology. 



Reichenbach, and served to restore tentatively confidence in the ho- 

 mology of the antennal glands of Malacostraca with the nephridia of 

 Annelids. Since that time the idea that the antennal gland is in part 

 mesodermic has gradually gained ground, but the question is still 

 treated in current writings as in a degree an open one, though nearly 

 all the text-books, following Reichenbach, state that it is entirely ecto- 

 dermic in origin. 



No one has repeated, as far as I know, Reichenbach's work on the 

 development of the gland in Astacus. With the exception of the work 

 of Boutchinsky ('95), 1 — which unfortunately is little known because 

 of its being in Russian, — no satisfactory account of the embryology of 

 the antennal gland in any Malacostraca has appeared since Kingsley 

 ('89) wrote. It seems probable, in view of the agreement of Kingsley, 

 Boutchinsky, and myself, that Reichenbach's figures and descriptions 

 are misleading, and that he entirely failed to see the endsac. Lebe- 

 dinski ('92, p. 231), however, endeavors to reconcile Reichenbach's 

 results with those of Kingsley, and with his own on the shell gland of 

 Eriphia, by holding that the mesodermic sheath described by Rei- 

 chenbach ('8G, p. 98) is homologous with the mesodermic constituent 

 forming the endsac in Crangon and in Eriphia. I do not think that 

 Lebedinski's point is well taken, because in Crangon, Eriphia, Gebia, 

 and Homarus the endsac appears before the ectodermic invagination, 

 whereas in Astacus — accepting for the moment Lebedinski's interpreta- 

 tion — it arises much later. Further, the mesodermic sheath described 

 by Reichenbach is, according to his own words, only an enveloping 

 sheath of connective-tissue elements and not at all glandular. This 

 sheath is recognizable in Homarus, where it becomes in part the in- 

 vesting sheath of the gland proper and of the vesicle, and in part the 

 tissue of the blood vessels, but has no part whatever in the formation 

 of the secreting epithelium. 



We now know that the antennal gland is of double origin — meso- 

 dermal and ectodermal — in Crangon (Kingsley), Gebia (Boutchinsky), 

 and Homarus. These, to be sure, are all in a rather limited group, the 

 Macrura ; but it is my belief that similar conditions will be found in 

 other Malacostraca. 



The ontogenetic development of the nephridia of Annelids has re- 

 ceived attention from many investigators since the pioneer work of Ko- 

 walevsky ('71). The stimulation to these researches in the earlier part 

 1 The preliminary paper was published a year earlier, Boutchinsky ('94). 



