REPORT ON THE CRINOIDEA. Ill 



may be seen in an optical section of the decalcified pinnule to end in a small rounded 

 opening. One of these openings is shown in PI. LIV. fig. 3, and I do not think that, as 

 a rule, there is more than one to each pinnule. 



In nearly aU the Crinoids which I have examined the structure of the genital gland 

 is the same as described by Ludwig in Antedon eschrichti. The epithelial lining of the 

 genital tube is continuous with that of the ovary. Individual cells of this lining enlarge 

 at the expense of their fellows, and are gradually enclosed in follicles which are derived 

 from the original ovarian epithelium. These follicles project freely into the lumen of the 

 gland ; but there is practically nothing which could be called an ovarian stroma. 



In Actinometra nigra, however, there is a highly organised stroma separating the 

 follicles ; and young ova may be found in it at all stages of growth, the smallest being 

 no laro-er than the nucleolus of a mature ovum. But I have been unable to make out 

 the derivation of these germs from the epithelial cells as clearly as may be seen in Antedon 

 eschrichti and similar forms. 



In Actinometra fxirvicirra, on the other hand, I have failed to discover any follicular 

 structure at all. The ova are smaller than in other types, and project slightly from the 

 surface of a dense brown stroma in which no organised structure can be made out 

 (fig. 4 on p. 113 ; PL LXI. figs. 3, 4). The genital cord of both these species (PL LXI. 

 figs. 5, 6) is very difi'erent from that of the other Crinoids, varying greatly in shape and 

 appearance. But the description and illustration of its peculiarities must be deferred to 

 another occasion. 



In two other multiradiate species of Actinometra from the Philippine Islands, 

 however, Actinometra dissimilis and Actinometra nohilis, the genital cord of the arms 

 is much less complex, and closely resembles that of Antedon eschrichti, except that it 

 frequently contains a quantity of ill defined pigment masses. The ovaries have the same 

 structure as those of Antedon eschrichti and Antedon rosacea; and the ova which they 

 contain, exhibit exactly the same relation between yolk and yolk-sac as have been 

 described by Ludwig in the ova of the latter type.^ The whole ovum appears to be 

 sm-rounded with a network formed of dark threads and clear meshes. The latter, 

 however, are larger, and the former smaller and more delicate than in the ova of Antedon 

 rosacea, as described by Ludwig. 



F. The Nervous System. 



That portion of the organisation of a Crinoid which corresponds to the ambulacral 

 nervous system of other Echinoderms is of a somewhat limited character. So far as is 

 yet known, it is confined to the ciliated floor of the food-grooves and to its mmute 

 lateral extensions in the direction of the tentacles. "Andere Zweige als die schon 



1 DiL- Bililung del- EiliiiUe bei Antedon rosacea, Zool. Anzeiger, Jahrg. iii., 1880, pp. 470, 471. 



