ME. P. H. CAEPEXTEE ON THE GENUS ACTLNOMETEA. 51 



as Alecto parvicirra by Midler 1 , who gave this name to three small spirit-specimens in 

 the Paris Museum, from the voyage of Peron and Lesueur in 1803, which I recently 

 found there under the name of Comatula simplex, Mus. Midler's diagnosis of Alecto 

 parvicirra was based upon his examination of the three Paris specimens, which all 

 have an excentric mouth and a terminal comb on the oral pinnules, and is exactly appli- 

 cable to Act. polymorpha, except that he describes the pinnules as " ziemlich gleichformig." 

 In their yellow colour and smaller size (about 100 millims.) these also differ slightly 

 from the type of Act. polymorphic, but without a very much closer examination of them 

 than I was able to make, it would be impossible to arrive at a definite conclusion as to 

 the identity or difference of these two species. 



The Vavao variety of Alecto parvicirra described by Miiller occurs in the Paris 

 Museum under the name of Comatula brevicirra, Troschel. This specimen differs from 

 Act. polymorpha in many subordinate characters, and is not absolutely identical either 

 with the type or with either of the four varietal specimens which I have examined ; 

 and I cannot but regard it as representing another of the slight and probably very 

 numerous modifications of this type, of which I think it most likely that Midler's 

 original species, Alecto parvicirra, is also a varietal form. 



(§ 34) The following diagnosis will, I believe, be found sufficient for the future iden- 

 tification of Act. polymorpha and of tbe four varieties here referred to. 



Actinometra polymorpha, n. sp. 



Centrodorsal piece. A circular or irregularly pentagonal disk almost completely concealing the first 

 radials. Surface flattened, and slightly concave in the centre. 



Cirrhi marginal, 15-25, of 11-1-1 segments, of which the fifth and sixth are the longest; hasal ones 

 thick, and wider than long; remainder taper gradually, and terminal ones are laterally compressed; the 

 last 5 or 6 segments have a small dorsal spine, increasing in distinctness up to the penultimate segment, 

 which hears the terminal claw. 



Radials 3, of which the first are barely visible ; the second are short, and in the middle of the same 

 height as the first, but somewhat lower at the sides, for nearly the whole length of which they are united 

 to one another in pairs. 



Axillary radial pentagonal, about twice as wide as the second, to which it is united by ligaments only. 



Arms from 13-40 ; rays may divide three times. First segments borne by each axillary in contact 

 for nearly their whole side. 



Distichals and Palmars. When present, 3 ; second bears a long pinnule, and is united to the first 

 by ligamentous articulation only. Axillary has a syzygium. 



Syzygia. First on third brachial, then an interval of 6 segments to the next, and then a general 

 interval of 3 throughout the arm, variable from 0-6, but usually varying to < 3. 



Arms. Anterior arms much longer than the posterior, which are usually non-tentaculiferous. Width 

 increases from 3rd to 10th segment, remains uniform till about the 14th, and then decreases, slowly 

 in the long anterior arms, and rapidly in the short posterior ones. Arm-segments wedge-shaped, slightly 

 overlapping one another, and fringed at the borders with short spines. 



Pinnules. The second distichal and the second palmar, when present, bear long pinnules, of which 

 the palmar bears the shorter one; the next is on the second brachial, and still shorter, and the length 



1 ' Gattung Comatula,'' p. 24. 

 SECOND SERIES. — ZOOLOGY, VOL. II. 8 



