102 



THE VOYAGE OF H.M.S. CHALLENGER. 



These may be classified very readily according to the characters of the cirri and lower 

 pinnules, as shown in the following scheme : — 



1. The Basic urva-gromp. 



The radials and lower brachials have flattened sides. 



A. Pinnule-ambulacra plated. 



I. Later cirrus-joints have dorsal spines. 



a. First pinnule smaller than the second. Eighty cirrus-joints, 



b. First pinnule longer than the second. 



1. Sixty cirrus-joints or more. 



Basal joints of first pinnule much flattened on the outer side. 



First two joints of the distal pinnules expanded and trapezoidal, 

 First pinnule but little flattened on the outer side. First two 



joints of distal pinnules not specially marked, 



2. Thirty to fifty cirrus-joints. 



(a) First pinnule flattened on the outer side. Cirri irregularly 



disposed, 

 (i.) Pinnule on third brachial carinate, like that on second, 

 (ii.) Pinnule on third brachial small, like that on fourth. 

 a. Calyx and arm-bases not spinous. 



* Second and third radials rounded, but not 

 specially convex. 

 Second radials very short, 

 Second radials of moderate length. Later 

 arm-joints carinate, . 

 ** Second and third radials sharply convex or 

 carinate. 

 Axillaries wider than long, 

 Axillaries longer than wide, 

 /?. Calyx and arm-bases very spinous. Arm-joints 

 with large curved spines, 



(b) First pinnule not flattened on the outer side. Cirri in ten 



vertical rows, ...... 



3. Less than thirty cirrus-joints. 



(«) Pinnule on third brachial a good deal smaller than that on 

 second. Arms spinous. First radials invisible, . 



(b) Pinnule on third brachial not much smaller than that on 

 second. Arms smooth. First radials visible, 



II. Less than thirty cirrus-joints without dorsal spines. 



a. Pinnules of eighth and following brachials have broad lower joints, and 

 strong plates covering the genital glands. 

 1. Third and fourth joints of genital pinnules broad and nearly flat on 

 the outer side, but the fifth joint smaller. 



(a) First radials concealed by centro-dorsal ; lower arm-joints with 



raised and crenulated distal edges, . . . < 



(b) First radials distinctly visible. Arm-bases smooth, . 



1. longiciira, n. sp. 



2. valida, n. sp. 



3. incerta, n. sp. 



4. gracilis, n. sp. 



5. lusitanica, 1 n. sp. 



6. breviradia, n. sp. 



7. spinicirra, n. sp. 



8. acutiradia, n. sp. 



9. bispinosa, n. sp. 



10. latipinna, n. sp. 



11. multispina? n. sp. 



12. echinata, n. sp. 



13. basieurva, n. sp. 



14. incisa, n. sp. 



1 This is also a Lidistichate species. See pp. 110, 217, and PI. XXXIX. fig. 1. 



2 This is also a tridistichate species. See pp. 117, 248, and PI. LXIX. figs. 1, 2. 



