WAITE : ANTENNAL GLANDS IN HOMARUS AMERICANUS. 171 



that for the shell gland of Phyllopods, as already worked out by Grobben 

 ('79^ p. 23), and later confirmed by Lebedinsky ('91, p. 152). 



Lebedmsky ('89, p. 197, see also '90, p. 184) has found that the 

 "• Scgmentalorgau " in the first maxilliped of Eriphia is formed from 

 both ectoderm and mesoderm, and from this he concludes ('92, p. 233) 

 that the antennal glands, the shell glands, and " Segmentalorgane " in 

 Crustacea are serially homologous organs. 



Allen ('93, p. 338) says that in a larva of Palsemonetes a few days 

 old the green gland consists of an endsac, which communicates by means 

 of a U-shaped tube with a very short ureter opening at the base of the 

 antenna, and that the distal portion of the tube is slightl}' enlarged and 

 may be termed a bladder. At hatching, the deeper part of the gland is 

 a mass of cells without lumen, but ureter and external opening are pres- 

 ent. Very early in larval life the cells of this deeper portion separate 

 from one another, giving rise to the lumen, and the gland probably be- 

 comes functional at that time. The development of the organ in the 

 larva consists chiefly in the enlargement of the bladder, which, arising 

 at the elbow of the U-shaped tube, grows mediad and dorsad to a great 

 extent. The shell gland, opening at the base of the second maxilla, is 

 the functional kidney during embryonic life, but it is not found in young 

 adults. 



In his later paper Allen ('93'') gives figures (Plate XXXVI. Figs. 1 

 and 2) showing that in the young larva the endsac differs histologically 

 from the tubule and bladder, the two last. being lined with an epithelium 

 composed of cells which are striated and capped with a cuticular struc- 

 ture. The plexus of tubules between the endsac and the bladder arises 

 from the original tubule in that region " obviously ... by the splitting 

 up of the single tubule" (p. 406). 



Boutchinsky ('95, pp. 78, 79, Tab. II. Fig. 51) found that in Iphinoe 

 the ectodermal part of the gland arises as a true invagination from the 

 exterior, with a lumen at all times connected with the outside world. 

 The deep end of this invagination is surrounded by a mass of meso- 

 dermic cells. In Gebia littoralis, at a stage (Tab. IV. Fig. 85) when 

 the telson has grown forward so that it is even with the mandibles, he saw 

 (pp. 169, 170) the first appearance of the antennal gland as a compact 

 ball of mesodermic cells (Tab. VI. Fig. 143) with distinct walls and 

 large granular nuclei. The ectodermic invagination occurs at a later 

 stage (Fig. 153), a lumen meanwhile having formed in the mesodermic 

 part of the gland. The mesodermic part soon elongates and becomes 

 horseshoe-shaped (Fig. 154). He reaches two general conclusions in 



