MONOGRAPH OF THE EXISTING CRINOIDS. 521 



The older stages have the stem and attaching disk of approximately the same actual size 

 as earlier, and therefore relatively much smaller. The stem joints have lost the encircling 

 ridge and are practically smooth ; the basals are relatively small, but the orals are still con- 

 spicuous; the cirri have begun to appear on the margin of the centrodorsal ; they have a variable 

 number of joints, of course, and are very erect, parallel with the arms; the latter have elongated 

 and the brachials are well defined. No syzygies are to be found, but the third and fourth 

 plates appear to be somewhat closer together than the others. 



One of the figures given by Wright in illustrating the type of Kallispongia 

 archeri, described by him as a new genus and species of sponge, probably repre- 

 sents a pentacrinoid of this species. 



Three pentacrinoids of this species at hand from off Manning River, New 

 South Wales, in 22 fathoms, are extremely young, the ends of the crescents from 

 which the columnals are built up apparently having just joined on the ventral side. 



The short and very stout column consists of 10-12 columnals, which are little 

 more than the primitive annuli, and a broad ring-shaped terminal stem plate 

 nearly three times the diameter of the column which occupies the center of a 

 large fleshy disk. 



At the top of the stem there is very clearly to be seen a circlet of rounded 

 infrabasals, apparently five in number, which are quite distinct both from the 

 topmost columnal and from the basals. 



The basals have very broadly rounded angles. 



The orals are rather narrow, with the distal portion rather strongly incurved. 

 Their edges are not everted nor modified in any way. 



CROTALOMETRA PORRECTA. 

 Figs. 1207-1209, pi. 34. 



On April 3, 1876, near Ascension Island (lat. 7 r>4' 20" S., long. 14 28' 

 20" W.) the Challenf/er dredged in 420 fathoms three pentacrinoids, which Car- 

 penter determined as belonging to Thalassometra multispina, for the reason that 

 this was the only 10-armed species found at this station. But the fact that the 

 pentacrinoids had 10 arms only is no evidence that they are not the young of a 

 multibrachiate species, since increase in the number of arms does not occur until 

 long after the larval column has been discarded. This, however, Carpenter did 

 not know. 



I am inclined to regard these pentacrinoids as the young of Crotctlometra 

 porrecta for the following reasons: 



Carpenter says that "they are relatively much larger and more robust than 

 the corresponding stages of any other species which I have seen, with the exception 

 of" Heliometra glacialis. Now ThaJassometra multispixa is a rather small species, 

 with arms only 50 mm. long, and it is unlikely that it would be characterized by 

 exceptionally stout larvae, while ('roUilotn.ctrn. />orrecta is a large and massive type, 

 with arms 150 mm. long, and would naturally be supposed to have larvae more com- 

 parable in size to those of Heliometra ylacialis. 



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