REPORT ON THE DEEP-SEA MEDUSAE. lxxxiii 



entire want of the gastral ostia (Solmaris and Solmoneta, System, taf. xix. figs. 10-12 ; 

 taf. xx. figs. 7-10). In consequence of this retrograde formation in Solmaris, the whole 

 gastrovascular system is reduced to a simple, lenticular, central stomach. 



§ 119. Pylorus or gastral opening ("porta pylorica, " gy). In most Medusae in 

 which the basal stomach is developed, the latter appears more or less sharply defined 

 from the central stomach by a circular constriction. We term this the gastral opening or 

 pylorus ; it comports itself above in the same way as the palatine opening does above, but 

 is wanting, of course, in all Medusae in which the basal stomach has undergone 

 retrograde formation. In the Anthomedusse, the only Craspedotae which have a 

 basal stomach or apical canal, the pyloric opening is a simple, circular stricture, and only 

 of special interest in the Cladonemidae, as it perhaps corresponds to the " funnel opening " 

 which separates the ectodermal " oesophageal stomach " from the endodermal ;t funnel 

 cavity" in the Ctenophorae (Ctenaria, System, p. 107, taf. vii.). The pylorus, like the 

 basal stomach, is usually wanting among the Acraspedae, in the Discomedusae or 

 Ephyroniae, whilst it is usually very pronounced in the Tesseroniae. In the Stauromedusae 

 the plyoric stricture is sometimes obliterated, sometimes deeply. inserted (taf. xv. figs. 2, 

 3, AB). In the Peroniedusae it is sharply defined by the proximal margin of the 

 coronal sinus (PI. XXI. figs. 12, 13, CD). Special " pyloric valves " (" valvulae pyloricae ") 

 which project inwardly from the four interradial angles of the quadrate stricture and 

 from the bottom of the four small pyloric pouches (" bursae pyloricae, " by), are often 

 developed in the Cubomedusae and in the Cannostomae. 



§ 120. Basal stomach or basal tube (" gaster basalis," vel " tubus cupolaris," also 

 termed " peduncle canal, peduncle tube, apical canal, or cone canal," gb). The basal 

 stomach is the third and uppermost of the three principal chambers of the central 

 principal intestine ; it is separated by the pylorus from the central stomach, and 

 corresponds to the peduncle tube or peduncle canal of the stalked polyps. It is lost in 

 the majority of Medusae, and only preserved by inheritance in a few groups. We only 

 find it among the Craspedotae in part of the Anthomedusae, where it appears as a simple, 

 narrow canal, which traverses the apical process of the umbrella cone, ending caecally in 

 the point of the latter ; the stomach of the germinating Anthomedusae was originally 

 connected by this peduncle canal with the stomach of the nursing Tubularia polyp (comp. 

 System, p. 5, taf. i., ii., iv., vii.) ; in many Cladonemidae it is inlarged into a spacious 

 apical cavity (" cavitas cupolaris "), which is sometimes occupied by the young brood 

 (Pteronema, Eleutheria). The enlarged pyriform apical cavity of the Cladonemidae is of 

 great interest as it probably corresponds to the funnel cavity of the Ctenophorae (System, 

 pp. 99, 107, taf. vii., Ctenaria), Among the Acraspedae the basal stomach is usually 

 entirely wanting in the depressed Discomedusae or Ephyroniae, whilst it is constant 

 and usually highly developed in the three other orders, the highly arched Tesseroniae, 

 It appears in the Stauromedusae (in the Tesseridae, PI. XV., and Lucernaridae, PI. XVI., 



