194 M. LEWIS NICKERSON, 



down flask-shaped processes containing the ampullœ into other cells. 

 The walls of the outer sack and their continuation as the outer wall 

 of the sheath, represent the boundary of the cell. This interpretation 

 has not, I believe, been offered by any other writer on the subject of 

 intracellular canals. Another and perhaps more satisfactory explanation 

 of the conditions is, that the ampullae, their sheaths and the primary 

 canals leading from them, are differentiations of the large gland cells 

 in which they lie , and that only the common duct with its chief 

 branches belongs to the cell containing the large nucleus surrounded 

 by the vacuole, which cell constitutes a sheath for the main duct. 

 Which of these is the true interpretation cannot be decided from 

 sections of adult worms, as in such sections it is impossible to make 

 out cell boundaries in the region where the several canals converge 

 to join the main duct. A comparison with the somewhat analogous 

 condition described by Zimmermann (1898) for Phronima, which will 

 be referred to in the latter part of this paper, renders the second 

 interpretation more probably correct. 



So far as I have been able to ascertain, intracellular ampullae 

 with their radial vesicles and canals, have not been noted previously 

 for the Gephyreans. That Andrews (1890) in his study of the ana- 

 tomy of Phascolosoma failed to find the intracellular structures de- 

 scribed in this paper, was probably due to the fact that his material 

 had not been well preserved. The vacuoles which he notes as 

 belonging to one form of epidermal organ, probably represent the 

 remains of the ampullie here described, although no mention is made 

 of any radiating threads, concentric sacks, or branching canals. 

 Structures in many respects similar to those found in these glands of 

 Phascolosoma are known to exist in certain glands of the Crustaceans 

 and Insects, and probably in the nephridia of the leeches. A few in- 

 stances which show marked resemblances to the structures described 

 in this paper will be briefly discussed. 



GiLSON (1889) describes for the odoriferous apparatus of Blaps 

 mortisaga, a condition which in its details shows many likenesses to 

 that found in Phascolosoma. The four parts which he mentions as 

 belonging to these intracellular structures, "une vésicule radiée, une 

 ampoule centrale, un tube excréteur mince et une gaîne du tube qui 

 est une formation analogue à la vésicule radiée", are ail present in 

 the case of Phascolosoma. In Blaps., however, there is no uniting of 

 canals, each one opening by its own duct to the exterior. Gilson 

 holds that the radiations surrounding the ampulhie are continuations 



