ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 541 



'has been derived from some species of Epenthesis, which, if not identical 

 'with, was closely allied to E. folleata. 



In P. pentata the lips show a decided tendency to revert to the 

 ancestral condition of four lips, but the radial canals do not, inclining 

 rather toward the production of even more than five canals. Those 

 with five radial canals show a decided tendency to have also five lips, 

 but the correlation becomes less and less perfect the more the medusae 

 depart from the normal. The greater the departure from the normal, 

 the less likely are the radial canals to be radially symmetrical, and the 

 more likely are they to be irregular. Among those in which the canals 

 are not radially symmetrical, 66*66 p.c. have these organs bilaterally 

 arranged ; and in the case of forms with non-radially symmetrical lips 

 71 p.c. are bilateral. When radial symmetry is lost there is a decided 

 tendency to bilateral symmetry. One half of the abnormal individuals 

 are radially symmetrical. 



The more abnormal the medusoids the less their fertility ; thus the 

 variability is a slight disadvantage to the species as far as productive- 

 ness is concerned. The reduced fertility and the prevalent irregularity 

 of the abnormal individuals may account for their inability to initiate 

 new species. Monsters with two manubria suggest the mode of origin of 

 polygastric forms, such as Gastroblasla limida, G. raffaelei, Multioralis 

 ■ovalis, Ac. 



The variations of P. pentata are closely similar to those of Epen- 

 thesis folleata, but more numerous. 



Thus Pseudoclytia pentata has all the interest of a new race ; it is 

 very successful ; it is very variable ; and in its variations it illustrates 

 the manner in which other newly-arisen races of animals may have 

 suddenly given rise to still more diverse species. The abnormal indi- 

 viduals labour under two disadvantages ; — they are less fertile, and they 

 are somehow handicapped by the disturbance of symmetry. 



Hydroids from the Pacific* — Dr. CI. Hartlaub describes the Hy- 

 droids obtained by Schauinsland's expedition, comprising fifteen species 

 from the South Island of New Zealand, all belonging to the Antarctic 

 fauna ; fourteen species of Arctic character from the vicinity of Van- 

 couver ; and a single species from the Sandwich Islands. Of the New 

 Zealand forms five are European, including the common Clytia johnstoni, 

 now first recognised as a member of the New Zealand fauna. 



Anatomy and Development of Cassiopea xaniachana.f — Dr. R. 

 P. Bigelow publishes a full account of this interesting medusa from 

 Jamaica, found by Dr. Field in 1891, and already briefly described. It 

 seems to differ only slightly from C. andromeda Eschscholtz and C. 

 polyplwides Keller, and it is possible that Fewke's C. frondosa is merely 

 a variety. The Jamaican specimens show great variability, especially 

 as regards the number of rbopalia and of marginal lobes in the para- 

 meres, points of importance, because the former character has been 

 regarded as of generic and the latter as of specific value. In both 

 cases the additional members are not intercalated fortuitously, but 

 manifest a constant regard for the symmetry of parts. In the endo- 



* Zool. Jahrb., xiv. (1801) pp. 349-79 (2 pis.). 



t Mem. Boston Soc. Nat. Hist., v. (1901) pp. 191-236 (8 pis.). 



