ASTEROIDEA 213 



a flat, embryonic midradial plate without a spinelet. These are probably the isolated 

 radial plates of the adult that are usually out of alignment with the paired costae. The 

 seventh arch near the terminal " complex" appears to have this radial plate. Irregularity 

 of plates at base of ray (arches i and 2) is foreshadowed by the appearance of secondary 

 plates and spinelets — the beginning of the differentiation of a genital region. The primary 

 radial plate can be recognized. In the third to seventh arches the spines are so spaced as 

 to give the appearance of a complete arch of spines of which there are 8 on the second to 

 fourth arches and 6 on the fifth to seventh. Proximally, 3 spines on either side have a 

 heavy sacculus, distally 2. Many of the mouth-plates have 3, but a few of them 2 

 marginal spines. In each mouth angle there has been a rapprochement of the first 

 adambulacral plates which are now nearly as in the adult. 



Some of the disk plates have an additional spinelet. The prongs of the spines are 

 slightly longer than in the preceding stage. 



(3) St. 123 (PL XVII, fig. 2); extreme diameter 34 mm.; R 13-17 mm., r375 mm. 

 The disk diameter of this well-preserved 13-rayed specimen is the same as that of the 

 preceding, but the unequal rays are longer, comprising 10 or 11 skeletal arches which do 

 not differ in character from those of the preceding specimen. The trilobate primary radial 

 plate with its prominently sacculate, aciculate spine is conspicuous. A smaller dorso- 

 lateral spine on either side usually has a smaller sacculus. The 3 or 2 lateral sacculi of 

 succeeding arches are large. Two spinelets, 0-57 and o-6 mm. long, from disk of this 

 specimen, are figured (Fig. G, i , i o). Only one of the 26 mouth-plates has 3 spines ; the 

 other have 2. 



(4) St. WS 42. Extreme diameter 60 mm. ; R 23-37 mm., r 5 mm. The short rays 

 may be regenerating the tips. Rays 13. The first appearance of papulae, there being 

 about 10 on the disk, situated interradially near margin. One ray has a papula near the 

 base. The genital region is swollen so that base of ray is convex and higher than plane of 

 disk. The lateral aspect of ray is similar to PI. XVI, fig. 3, but smaller, and no papulae 

 are present adjacent to adambulacral plates. The base of rays are closely appressed and 

 dorsolateral spinelets interdigitate, but no permanent spine bridges have been formed. 

 There are 18 skeletal arches, complete and incomplete, and the dorsal aspect of ray is 

 similar to adult. The sacculi are large and subglobose. Most of the lateral ribs have 3 

 spines and sacculi; sometimes on outer part of ray, only 2, as in the fully adult. Each 

 mouth-plate has 4 or 3 marginal spines. 



Food. Samples of stomach contents of specimens from Sts. 42 and 1 23 were submitted 

 to Dr Isabella Gordon for determination. 



St. 39. The exoskeletons of 4 Cumacea, probably Gaussiciima were found in the 

 stomach of the type. (W. K. F.) 



St. 42. Specimen A : remains of Cumacea and small Mysidae. (W. K. F.) Specimen 

 B. " Cumacea of the family Bodotriidae (as used by Zimmer, 1927). Appear to be males 

 of Gaussiciima, a genus hitherto know only from females." (Gordon.) 



St. 123. Largest specimen (R 100 mm.), a few Cumacea. (W. K. F.) 



Small specimen (PI. XVII, fig. 2). When first removed from bottle a number of 



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