OX A NEW SPECIES OF CORYMORPHA FROM JAPAN. 



155 



ciles as in C. nutans. The gonosomes, which arise from the hyposomal 

 basis just above the proximal tentacular row, are comparatively long 

 (7-10 mm.) and slightly thicker than proximal tentacles. They are 

 not very contractile, so that they remain almost unchanged in length 

 after being killed. The number of the gonosomes vary to some extent 

 according to age of the hydroid ; in the larger individuals it ranges 

 from 8 to 15. They are arranged in a single circlet. All the speci- 

 mens examined by me possessed 8- 11 medusa-bearing gonosomes, the 

 rest being still rudimentary and devoid of medusae. The number and 

 arrangement of the above organ clearly distinguish the species from 

 its nearst from, C. nutans, which has 15-20 gonosomes arranged in two 

 alternate rows. The stem of a full grown gonosome gives off 10-15 

 short branches, which all lie on the outer side of the stem in two al- 

 ternate rows. To the free end of such a side branch a certain num- 

 ber of medusoid gonophores are attached in a cluster. The latter are 

 in quite various stages of development (fig. 2), some being simple bud- 

 like prominences, others being bell-shaped, and still others already 

 bearing a single tentacle. The general shape of the umbrella resembles 

 considerably that of C. palma Torrey,^ but the manubrium is nearly 

 as long as the umbrella. Some old medusae still in attachment have 

 the mouth and long, somewhat moniliform tentacles, but seem to be 

 destitute of gonads. Unfortunately such advanced medusae dropped 

 off and were lost when killed. 



As is the case with other Corymorpha species as well as with 

 Branchiocerianthus and many tubularian hydroids, the hydranth-cavity 

 is divided into an upper and a lower, less spacious compartment (fig. 

 3, hp. c. and /. h. c). The two cavities communicate with each other, 

 as was pointed out by Allman in C. nutans, by means of a narrow 

 vertical passage. This canal-like passage is produced, it may be said, 

 by an extensive development of the thick parenchymatous tissue (p. t.) 



I) Torrey H. B.,— Biological Studies on Corymorpha ; 11 The Development of C. palma 

 from the Egg. (Univ. of Calif. Public, Zool., vol. 12, 1907). 



