64 ANATOMY OF THE ENOPLA. 



covered with them; continued pressure causing them to escape into the reservoir, and pass forward 

 into the ejaculatory duct. The curved fibres have a laminated appearance posteriorly. Circular fibres 

 are clearly indicated in this species by the peculiar contractions of the inner wall of the reservoir 

 (Plate XII, fig- 6) . The latter has more translucent walls and greater mobility than in A. lactifloreus, 

 and the coats are diminished in total bulk posteriorly, so that the channel of communication is short. 

 The glands of the reservoir are large transparent structures, with clear globules in their interior, 

 and differ in general aspect from any hitherto observed. Those of the posterior chamber of the 

 organ are larger than in A. lactifloreus or Tetrastemma. Occasionally several stylets lay in 

 the cul-de-sac of the latter division, showing that they had passed along the ejaculatory duct, or 

 that the reserve-stylets had fallen into the cavity behind, and thence made way through the 

 reservoir into the posterior chamber ; unless we are to suppose they had been formed in the latter. 

 When the proboscis of this species is everted (Plate XIII, fig. 19), the central stylet projects 

 much less than in A. lactifloreus. The cavity behind the central apparatus becomes elongated, 

 apparently by the encroachment of the marginal stylet-sacs. There is no appreciable space at 

 the base of the central stylet, which (space) in A. lactifloreus forms the small umbrella (e) in this 

 position. The floor of the anterior chamber is less differentiated, and the spiral muscles of the 

 reservoir less bulky. 



Dr. Johnston observes of this species, "that the structure of the stomach" (proboscis) "is like 

 that of its congeners, excepting in there being five or six spines on each side of it, instead of 

 three, which is the usual number." He does not refer to the peculiar arrangement of the 

 central stylets, though an incomplete woodcut in one of his early papers shows that it had not 

 entirely escaped the notice of his accomplished artist. In fig. 19, Plate C, of the 'Voyages de la 

 Commission Scientifique du Nord, en Scan din avie,' the structure of the central apparatus of 

 this species is also fairly shown. 



The proboscis in Amphiporus spectaiilis has a faint pinkish hue. My sole specimen was 

 partially decayed before examination, but it was at once apparent that no extraordinary curved 

 horny comb as described by M. de Quatrefages existed in the place of the central stylet. The author, 

 however, does not speak with certainty on the subject, since he states that he regrets he had mis- 

 laid his drawing of the actual relations of this organ to the other parts. The whole structure is 

 essentially that characteristic of the Amphijjorina, as represented indeed by Professor Keferstein. 



The organ is comparatively large in Ampkiporus hastatus, and the glands of the ante- 

 rior region coloured of a pale brownish or dull yellowish hue. The central portion of 

 the stylet-region (Plate XXIII, fig. 18), has its basal granular apparatus very slightly con- 

 stricted towards the posterior third. The muscular investment of this structure presents a 

 pale brownish appearance by transmitted light, whereas it is usually colourless. Behind is a 

 cavity homologous with that found in A. quicker, but much less capacious. The region is 

 peculiar in having four marginal stylet-sacs, which occupy nearly the same level in the organ at 

 different points of the circumference, and thus the pairs are not separated from each other, as 

 represented by M. de Quatrefages in his Folia armata (a Tetrastemma), by a considerable antero- 

 posterior interval. Each sac has the usual appearance and size, contains two or three perfect 

 stylets, some free granules, and is connected with the floor of the anterior chamber by a duct. 

 The external granular glands are well developed, and there are many larger globules amongst 

 the others, sometimes resembling a nucleus in the midst of surrounding granules. The peculiar 

 elasticity of the fibres composing the longitudinal layer of the proboscis is conspicuous in specimens 



