REPORT ON THE CRINOIDEA. 319 



round the calyx, though four of them are missing in one of Reguault's specimens. The 

 Philippine example presents a curious abnormality, the second distichal of one ray being 

 axillary, though not a syzygy ; while one of its two arms having been broken and 

 regenerated has developed a palmar series. But with this exception, I have never seen 

 any specimen which presents the general characters of Actinometra jimbriata and possesses 

 palmar series. Its most important distinctive character is the shape of the lower brachials. 

 The first half-dozen joints are nearly oblong in outline, as in almost all Comatulse ; but 

 their successors do not become triangular or quadrate as is generally the case. For they 

 remain short and wide, with nearly equal sides, so that their ends are much less oblique 

 than usual (PL LXII. fig. 3). It is this character more especially which distinguishes 

 Actinometra Jimbriata from Actinometra coppingeri and Actinometra midtiradiata (PI. 

 LX. figs. 1,2; PI. LXVI. fig. 1). By the twenty-fifth brachial, or sooner, the joints are 

 almost perfectly oblong, and they remain as thick disks till near the end of the arm, where 

 they become squarer and finally slightly elongated. The joints of the middle and lower 

 parts of the arms overlap one another to a greater or less extent, and their edges are 

 fringed with small spines ; but there is much variation in both characters. 



This thickly discoidal shape of the arm-joints appears to be their highest form of 

 development. A study of regenerated arms of different sizes shows that the joints are 

 at first elongated as they are in the Pentacrinoid, and that their gradual increase in width 

 makes them at first quadrate, then triangular, and finally more or less distinctly oblong, 

 this being the shape which is characteristic of the Pentacrinidae and of many fossil 

 Crinoids. We may perhaps say then that Actinometra cop>pingeri and Actinometra 

 multiradiata, with their more triangular joints at the bases of the arms (PI. LX. figs. 

 1, 2; PL LXVI. fig. l), are permanently immature forms of Acti, w met ra Jimbriata 

 (PL LXII. fig. 3), standing to it in the same relation as Antedon quadrata to Antedon 

 eschrichti. 



The mouth of Actinometra Jimbriata is radial, being usually distinctly excentric. and 

 sometimes quite close to the margin of the disk, the anal tube being central or nearly so 

 (PL LXII. fig. 4), while the hinder ambulacra embrace it in a horseshoe-like curve. 

 But in the Philippine specimen the mouth is almost central, the anal tube greatly 

 reduced, and the ambulacra grouped like those of Antedon. The two primary ambulacra 

 of the B ray are separately connected with the peristome, the outer one supporting but a 

 single arm, as distichals are undeveloped, while the posterior one is connected to the 

 peristome by a short trunk which is common to it and to the single groove that supplies 

 the whole of the postero-lateral ray C (PL LXII. fig. 2). 



The lower pinnules of this individual have somewhat carinate basal joints, but the 

 extent of the carination varies greatly, and it seems to be almost entirely absent in one 

 of the Banda specimens, though present in the others. It occurs in a form from 

 Madagascar, which, so far as I can judge from my notes of its other characters, appears 



