REPORT ON THE DEEP-SEA MEDUSAE. 59 



has a peculiar construction, which however could not be more minutely investigated as 

 the tentacles were not sufficiently well preserved. The ectodermal cells in the central 

 sucking-pit are much flatter, and without nematocysts (fig. 16, x). The muscular plate, 

 consisting of strong longitudinal fibres (m), lies immediately under the ectoderm (q). 

 Then comes a thick gelatinous supporting plate, which acts as elastic extensor against 

 the pull of the longitudinal muscular fibres, and re-extends the contracted tentacles, 

 shortened by the latter. In the sucking-cup the gelatinous fulcral lamella forms a 

 peculiar thick cap (fig. 163'), which encloses the csecal end of the tentacle canal and is 

 sharply divided by a distinct boundary line (z") from the thinner gelatinous plate of the 

 peduncle (z"). The endoderm (d) forming the epithelium of the tentacle canal (ct), 

 consists of high, dark-brown pigmented cylindrical' cells, having numerous unicellular 

 glands distributed among them. The csecal distal end of the tentacle canal shows a 

 very peculiar condition unknown to me in any other Lucernarid. The end of the 

 canal is closed by a conical wedge, which completely fills the distal end of the lumen of 

 the tube and is enclosed by endoderm. This axial wedge of the sucking-cup (fig. 16, y) 

 dyes a much more intense dark red with carmine than any other part of the tentacle. 

 It contrasts sharply with the yellow-brown endodermal cells enclosing it, and seems 

 composed of roundish corpuscles, thickly pressed together, which refract light strongly 

 and look like nematocysts. This axial wedge of the sucking-cup perhaps serves as a firm 

 support during its adhesion. 



The formation of the gastrovascular system (PL XVI. figs. 2-7; PI. XVII. figs. 13-16) 

 does not differ essentially in our Lucernaria from that known in other species of this 

 genus ; it lies between the simpler formation of the Tessericlse (PI. XV.) and the more 

 developed formation of the Periphyllidae (Pis. XVIII. -XXII.). As in the Tesseridse it is 

 divided into a central princij)al intestine (" gaster principalis "), and a peripheric coronal 

 intestine (" gaster coronalis "), communicating by four perradial gastral openings (go). 

 The principal intestine consists of three parts, viz., the aboral basal stomach in the 

 peduncle, the central stomach, and the freely projecting buccal stomach or oesophagus. 

 The central stomach is separated from the basal stomach by the pyloric opening (" pylo- 

 rus"), and from the buccal stomach by the palatine opening ("palatum"). The basal 

 stomach (" gaster basalis," (76) is the peduncle canal already mentioned; it passes through 

 the entire length of the peduncle, and ends cascally in its oral basis, whilst it opens at 

 the oral peduncle end by the pylorus (gy) into the central stomach. The basal stomach 

 originally presented a simple cylindrical or Cjuadrangularly prismatic hollow space, corre- 

 sponding to the " apical canal" of the Tesseridse. As the four interradial tseniola (ft) 

 project from the wall of the peduncle into the stomach, they divide its periphery into the 

 four perradial peduncle grooves or half canals already described (fig. 13, cp). In this 

 way the basal stomach acquires in transverse section the characteristic regular cross 

 shown in fig. 13, Plate XVII. The central stomach (" gaste centralis ") has usually a coni- 



