ME. P. H. CAEPENTER ON THE GENUS ACTINOIVIETEA. 117 



Q'. Notcies on the iunei- margins of the dorsal faces of the first radials. 



q. Radial depressions on the centrodorsal piece. R. Rosette. 



''i. >"2> '■•'''• Firstj second, and axillary radials. r.ar. Radial areas on the centrodorsal piece. 



r.c. Diverticulum from the radial ccelom into the substance of the first radial. 



r.co. lutraradial commissure. r.o. Central opening of the rosette. 



r.tn. Muscles between the first and second radials. r.s. Rachal space. S. Rays of the basal star. 



-Si, Sc,, /S3. Diverging, vertical, and lateral fibres effecting the interradial portions of the synostosis 



between the centrodorsal piece and the radial pentagon. 

 s. Depressions at the central ends of the rays of the basal star. 

 spi, sp.a. First and axillary suprapalmars. Sy. Syzygium. 



t. Short processes at the angles of the centrodorsal piece. 

 U. Sockets for the attachment of the dorsal cirrhi. 

 u. Inner openings of the cirrhus-canals in the centrodorsal piece. 

 v.i.f. Ventral interradial furrow. v.r.f. Ventral radial fui-row. 



V, W, X, Y, Z. The five primary basal cords proceeding from the angles of the quinquelocular organ. 

 Vi, Fo, Wu Wc,, Xi, Xj, Fi, \\, Z„ Zc,. The ten secondaiy basal cords produced by the bifurcation of 



the primary ones. 

 i'„ vo, ?f „ ^2, x^, ^2, Vv Vv ~i, ~2- The apertures in the basals through which the secondary cords pass. 

 V, < to, lu, X, 3}, y, y', z, z . The corresponding apertures of the central canals on the internal faces 



of the first radials. 



In PI. II. figs. 9-11 indicate the position of the mouth (ventral) relative to the radial skeleton 



(dorsal) . 

 * In PI. V. fig. 4 indicates the passage of the ventral radial canal into the central calcareous network 



within the radial pentagon by two openings, instead of by only one as usual. 



Plate I. 



Diagrams of the distribution of the ambulacra on the disks of different species of Comatula. The red 



lines mark the interradial intervals. Figs. 1-4 copied from Miillcr. 

 Fig. 1. Antedon rosacea. Fig. 3. Act. Wahlberyhii. 



2. Actinometra Solaris. 4. Act. muUiradiata. 



In figs. 5-16 the tentaeuliferous grooves are marked by dark lines, and the non-tentaculiferous 

 grooves by fainter lines. 



Fig. 5. Act. Solaris. Proportion of non-tentaculiferous arms, ^ 



6. Act. polymorpha : Type. „ i^ 



7. „ „ }> ^ 



8. „ „ }> 2b 



9. „ Var. 1. „ M 



10. „ Type. „ 4f 



11. „ „ i> M 



13. „ „ » 2 8 

 13. yy yy Jy 2'S 



14. „ Var. 2. „ ^ 



15. „ Type. „ M: 



16. Var. 4. All the arms tentaeuliferous. 



IG" 



