ZOOLOGY AXD BOTAKT, MICROSCOPY, ETC. 255 



possession of bunches of minute spines, enclosed in a thick skin-bag, 

 and resembling in form " long-stemmed agarics, or parasols with small 

 shades." They are, however, more remarkable for their arrangement 

 than for their form. This was in two or even three parallel vertical 

 rows, instead of the " unvarying single row of articulated spines which 

 is found in all known living Ophiurids." As the author points out, it 

 is not necessary to inquire whether they are spines or pedicellariae, in- 

 asmuch as pedicellariffi are only modified spines ; " but it may be said 

 that their supplementary character and abnormal shape give these 

 parasol spines the position of what used to be carefully distinguished 

 as pedicellarife." 



Ophiotholia appears to be closely allied to Ophiomyces ; both the 

 new genera would seem to be lowly in character, for they have no 

 radial shields, are but imperfectly calcified, and retain throughout life 

 the division of their arm-bones into two longitudinal halves. 



The author is of opinion that, as one species was dredged at 82 

 fathoms near the Barbadoes, and the other from 1350 fathoms near the 

 Fijis, we have only to consider the differences of locality, light, pres- 

 sure, and temperature, to develope some scepticism as to the influence 

 of " environment " in determining structure. 



Professor Lyman at the same time describes three new genera : — 

 Ophiocymhium, Ophiocliyton, and Ophiamhix. Altogether 167 new 

 species and 20 new genera of Ophiurids and Astrophytids were 

 brought home by the ' Challenger.' 



Ccelenterata. 



Early Stages of Renilla.*— Mr. E. B. Wilson has been studying 

 the development of this Pennatulid, and here gives a preliminary 

 account of his investigations. The larva, which exhibits a well- 

 marked bilateral symmetry, is ciliated, and at first swims actively. 

 The first pair of zooids is indicated by two slight elevations ; the 

 septa are unequal in length, but bilaterally symmetrical. After 

 ceasing to swim about freely, eight pinnate tentacles become developed 

 at the free end, the lateral zooids divide into chambers, and a median 

 zooid appears on the upper side, and in front of the lateral zooids. This 

 ultimately becomes the central zooid (" Hauptzooid " of the German 

 describers), through which the water of the colony is chiefly dis- 

 charged. Some time before this the characteristic spicules put in 

 their appearance^ At a still later stage we find the lateral zooids with 

 well-developed tentacles, and there are also four new pairs ; all these 

 develope into sexual zooids, and in addition to them, and after a mode 

 of development exactly the same, there appear rudimentary zooids. 

 " The subsequent development consists in the growth of these sexual 

 zooids, the constant development of new ones in the angles between 

 contiguous pre-existing sexual zooids, and the appearance of a series 

 of rudimentary zooids on the upper side of each sexual zooid. And at 

 length each rudimentary zooid, with the exception of the median 

 ' Hauptzooid,' multiplies to form a group of similar zooids."' It is 



* Amer. Jonrn. Sci., cxx. (1880) pp. 446-50 (1 pi.). 



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