154 BULLETIN OF THE 



I have mentioned above that two Pentacrinoids were entangled in the 

 cirrhi of the type specimen of Act. meridionalis from Charleston. They 

 presumably belong to that species, and are therefore interesting as being 

 the first Actijiometra Pentacrinoids that I have seen. The smaller one 

 is at about the stage represented at Fig. LB on Plate XXXIX. of Dr. 

 Carpenter's memoir on Ant. rosacea ; * while Fig. 1 . C on the same plate, 

 and Fio-. V. on Tab. V. of Sars's " Crinoides Vivants," t correspond to the 

 condition of the larger specimen, which has seven arm-joints beyond the 

 radial axillaries. The oral plates of the former are plainly visible, but 

 in the latter it is difficult to make out the condition of the disk. The 

 radials, however, are broader and more closely united than in the cor- 

 responding stage of Ant. rosacea, and their superolateral angles are much 

 less truncated. The basals form a closed ring, and the centrodorsal is 

 scarcely larger than the stem-joints immediately below it. Five of 

 these are short and discoidal, and the next joint much elongated. In 

 both these respects the Charleston Pentacrinoids resemble Ant. Sarsii 

 rather than Ant. rosacea. As in both these species the lower arm-joints 

 do not bear pinnules at first, but, with the exception of the second 

 brachial, do not accpiire them until a much later developmental stage. 

 Both in Ant. Sarsii and in Ant. rosacea the first pinnule appears on or 

 about the twelfth joint of the growing arm ; and it is not until some 

 time later, after several pinnules have been formed towards the end of the 

 arm, that any appear, even on the second brachial. In fact, the basal por- 

 tions of the arms of Ant. rosacea remain without piimides until after the 

 development of ten cirrhi on the centrodorsal and its separation from the 

 stem. But in Ant. Sarsii, which retains its stem until twenty or thirty 

 cirrhi have appeared, all the lower arm-joints acquire pinnules before 

 the close of the Pentacrinoid stage. So far as can be judged at present, 

 this appears to be a somewhat exceptional condition ; for I have found 

 five other species besides Ant. rosacea in which the third and the follow- 

 ing arm-joints do not develop their pinnules until some time after the 

 loss of the stem. Thus a very young Act. meridioialis has a relatively 

 large well-combed pinnule on the second brachial, and another faii'ly 

 large one on the eighth brachial. The intervening joints have small or 

 poorly developed pinnules, that of the fifth brachial being either a mere 

 stump or absent altogether. In a young Antedon from Station 231 the 

 7th to the 9th arm-joints have no pinnules. A young example of another 

 species of the same genus (locality unknown) has a large pinnule on the 



* Pliilosophical Transactions, CLVL, 1866. 



t Mcmoires pour servir a, la Connaissance lies CiinoiJes Vivants. Christiania, 1868. 



