686 MONTGOMERY— MORPHOLOGY OF THE [April 24, 



the mid-gut cseca of Amphipoda (Bruntz, 1903) ; the mantle in the 

 Cirripedia (Gruvel, 1894) ; and connective tissue cells of Copepoda 

 when the antennal and maxillary glands are lacking (Nemec, 1896). 



27. Onychophora ( Protracheata). 



Nephridia. — According to the observations of Balfour (1883) 

 and subsequent investigators, one pair of nephridia occurs in each 

 trunk somite, i. e., one pair to each pair of legs, except in the 

 penultimate or antepenultimate segment. Each opens ventrally at 

 the basis of a leg, and consists of an outermost excretory bladder, 

 a loop and a nephrostome that opens into the coelom ; but the portion 

 of the coelom that has such a connection is, as in the case of the 

 antennal and maxillary glands of the Crustacea, completely ab- 

 stricted from the remainder of the coelom and with excretory func- 

 tion, therefore each such coelomic sac may rightly be considered a 

 closed inner end sac of the nephridium. This is in agreement with 

 the facts of the embryogeny, as detailed by Sedgwick (1885-8) and 

 Evans (1901), according to whom each right and left coelomic sac 

 pinches into a dorsal and a ventral portion, and the latter portion 

 sends an outgrowth reaching to and opening at the leg. 



The salivary glands and genital ducts develop like the nephridia 

 and represent them in segments where they are lacking, are accord- 

 ingly homodynamous with them (Sedgwick) ; and the receptaculum 

 ovorum is homodynamous with an end sac of a nephridium (Evans). 



Anal Glands. — These also have been considered homologous with 

 nephridia by v. Kennel (1885). But Purcell (1900) has indi- 

 cated that the so-called " accessory glands " of the postgenital seg- 

 ments may rather be dyshomologous ; that while those (anal glands) 

 of the American Pcripatns are nephridia, those of other genera are 

 probably ectoblastic crural glands. 



Nephrocytcs. — There are medio-dorsal bands of these, also 

 masses of them near the bases of the legs (Bruntz, 1903). 



28. Insecta. 

 Malpighian Vessels. — These are absent in Japyx (Grassi, 1888) 

 and also in the Collembola where Folsom and Welles (1906) found 

 that the whole vcntriculus is excretory and periodically moults its epi- 



