REPORT ON THE CRINOTDEA. 281 



in Actinornetra pectinata, and is sometimes almost indistinguishable, even on the dry 

 arm. 



In Midler's own description of Actinornetra Solaris he noticed that the lower joints of 

 the second pinnule "zeichnen sich durch ihre Erweiterung aus." 1 He had made nearly the 

 same statement in his previous description of Asterias pectinata;- and when re-describing 

 the former species, from a specimen in the Hamburg Museum, 3 I pointed out that in 

 the pinnules of the fourth to seventh brachials the second and third joints are wide, with 

 strong and expanded dorsal keels, mentioning at the same time the variations of this 

 character which I had found in the original types of the species at Paris and Vienna. 

 Neither of these forms had any indication of a keel on the lower joints of the first pair of 

 pinnules; and this character, together with the larger number of cirrus-joints (over twenty), 

 then appeared to me to constitute the special marks of Actinornetra Solaris as distinguished 

 from Actinornetra pectinata, with its thirteen cirrus-joints and traces of keels on the 

 basal joints of both the first pinnules, in addition to those on the second pair. 



Since examining all the "Alert " collection I find that this view will still hold good, 

 except for one point, the occasional presence of a distinct keel on the pinnule of the third 

 brachial in Actinornetra Solaris. I have only found it in three individuals from Billiton 

 and in one from Port Molle. As a rule, however, there is no more indication of it than 

 is shown in PI. LIII. fig. 10, and the base of this pinnule, like that of its predecessor on 

 the second brachial, is not specially marked (PL LIII. figs. 3, 4). On the fourth and 

 fifth brachials, however, the case is different. The second and third, with sometimes 

 the fourth and even the fifth joints of their pinnules, have large and prominent keels 

 (PL LIII. figs. 11, 12), traces of which may generally be found on the pinnule of the 

 sixth and sometimes on that of the seventh brachial. In Actinornetra pectinata, on the 

 other hand, there are never more than two joints, and sometimes only one, which has a 

 definite keel, and this keel may appear on the pinnule of the second brachial, as in some 

 individuals from Bohol. It is usually present on those of the third to fifth brachials, and 

 sometimes on that of the sixth as well (PL LIII. figs. 17-20). But as a rule it is absent 

 in the latter case, and I have never seen any individual with the other characters of 

 Actinornetra pectinata, which has any sign of a keel on the pinnule of the seventh 

 brachial. Broadly speaking, then, we may say that there are not more than two, and 

 sometimes only one carinate joint on the lower pinnules of Actinornetra pectinata ; that 

 keels are generally present on the pinnules of the third, fourth, and fifth brachials, and 

 sometimes on those of the second and sixth, but never on that of the seventh brachial. 

 On the other hand, Actinornetra Solaris generally has two carinate joints, and occasion- 

 ally sometimes three or even four, on the pinnules of the fourth, fifth, and sixth brachials, 

 sometimes on those of the third or seventh, but never on that of the second. 



i AbJmndl. d. k. Ahad. d. Wiss. Berlin, 1847 [1849], p. 248. 2 Archivf. Naturgesch., 1843, Jahrg. ix. Bd. i. p. 134. 

 3 Journ. Linn. Soc. Lond. (Zool.), 1882, vol. xvi. p. 515. 



(ZOOL. CHALL. EXP. — PART LX. — 1887.) 0°0 36 



