20 ME. P. H. CAEPENTEE ON THE GENUS ACTINOMETBA. 



a terminal comb. These two characters, however, do not always coexist; forPonrtales 1 

 describes Antedon meridionalis, A. Ag., as having an excentric mouth, while he says 

 nothing about the first pinnule, except that it is "rather long, the first five or six joints 

 webbed by the perisome." 



Again, in many of the Comatula with an excentric mouth which I have examined, 

 the terminal comb is not limited to the oral pinnules only, but may occur at intervals on 

 different pinnules till near the end of the arms, although it is never so well developed as 

 it is on their basal or oral pinnules, fewer of the terminal segments bearing the processes 

 which go to make up the comb. 



Loven 2 has found the same to be the case in the new Comatula which he has described 

 under the name of Phanogenia typica. Speaking of the pinnules, he says, on p. 232 : — 

 " In nonnullis (omnibus ?) articuli 8 1. 9 ultimi convoluti, pectiuati, margine cujusvis ex- 

 terno in laminam lanceolatam niagnam erectam producto ; " but he goes on to say (p. 233). 

 " Os centrale. Tubus analis crassus in media area interradiali. Sulci tentaculiferi fere 

 quales in Antedone." 



Here, therefore, a terminal comb on the pinnules coexists with a central mouth ; so 

 that all the four possible variations may occur of these two characters, viz. the position of 

 the mouth aud the condition of the terminal segments of the pinnules. 



Thus Antedon rosacea Sac. have a central mouth and no comb. 

 „ Phanogenia tijpica lias a central „ and comb. 



„ Actinonielra Solaris kcAmvean excentric „ and comb. 

 „ Comatula meridionalis lias an excentric ,, and no comb. 



Leaving Phanogenia out of consideration for the present, as it was unknown to 

 Johannes Midler, the following scheme will represent the relations of Antedon, and Act i- 

 nometra as used by Dr. Liitkeu and myself, to Alecto and Actmometra as used by 

 Midler :— 



Alecto. Ambulacra symmetrically | mouth central. Antedon. Oral pinnules not specially 



distributed on the disk. J mouth excentric. "^ distinguished. 



Actinomctra. Ambulacra unsymmetri- ] fActinometra. Oral pinnules nearly 



cally distributed on the l mouth excentric. | always have a ter- 



disk. J minal comb. 



(§ 15) "We are now in a position to investigate which species of the numerous Coma- 

 tulcB described by Midler can be referred to Actinometra under its new definition, and 

 what further subdivisions of the genus are possible according to the principles of classi- 

 fication introduced by Midler. Before doing so, however, it will be advisable to devote 

 a little time to a consideration of the descriptive terminology which he employed, and 

 of the manner in Avhich it has been modified by later writers. 



In Pentaerinus and Comatula Miiller regarded the arms as starting directly from the 

 five radial axillaries. The two primary arms borne by each of these might either remain 



1 hoc. cit. No. 11, p. 355. Pourtales bcre evidently uses Antedon as equivalent to Alecto, and not in the sense in 

 ■which it was employed by Mr. Norman, viz. to designate those forms only in -which the mouth is central (or nearly 

 so) and the anus lateral. To avoid confusion, I shall speak of this species simply as Comatula meridionalis. 



■ " Phanogenia, ett hittills okiindt slagte af fria Crinoideer," Ofver. af Kongl. Yetensk.-Akad. Forhandl. 1SGG, 

 No. 0, p. 223. 



