106 I\Ir. W. K. Fislior'.-^ Soles on Asleroidea. 



seems to be more nearly allied to Pedicellasler than to either 

 Heliaster or to any of the recently proposed genera o£ 

 Asteriidre. I would tlicref'ore place Lahidiaster in tiie Pedi- 

 collasterida?. I have dissected a large example of" Lahidi- 

 aster mdiosini, Liitkon^ from the Straits of Magellan. 



Labididster differs from Bris'inga, Odinia, Freyella, and 

 similar genera in the following important particulars : — 



(1) Its abactinal skeleton is not duplicated in tiie Brisingidse ; 



(2) forticiform, or straight, pedicellariaj are present ; (3) the 

 adambulacral plates are crowded, very short in proportion to 

 width, and entirely unlike in form and armature the same 

 iiighly jieculiar j)lates of all Brisiiigid;e ; (4) the ambula- 

 craiia are shorter, especially the dorsal ends, which overlap, 

 or imbricate with, the next adoral ambulacra! plate, while in 

 the Brisingidai there is no sign of imbrication, the ambula- 

 cralia resembling the centra of chordate vertebrae, with vertical 

 articulating adoral and aboral facets. 



In the Brisingida3 (in the narrower sense) the abactinal 

 skeleton of the rays is variable, being in the form of trans- 

 verse, indei)endent, par;dlel ridges or costse, separated by 

 areas of integument without plates ; or the intervals may be 

 partially or conipletel}* filled in with more or less imperfectl}' 

 developed plates immersed in the body-wall ; or the arches 

 may be absent and a tessellation of thin plates may cover 

 the genital region of the ray ; or there may be thin plates, 

 more or lessspiniferous, together with differei:tiated transverse 

 costfe. 



Ill Labidiaster the skeleton of the ray is closely similar to 



volseUatuSj.hriareits, and haliceptis. Coronaster includes Heterasterias,' 

 \'errill, type Asterias. volseJlata, Sladen. In the above paper the following 

 remarks occur : — " The family affiliations of Voronader are not easy to 

 determine, its lineage being somewhat involved. The tendency to 

 crowding in the arrangement of pedicels partakes of the Asteriidie, while 

 its mouth-plates are quite as ' brisingoid as those of Odinia, and perhaps 

 more so than the oral angles of Labidiaster, two groups placed in the 

 Brisingidse. Its skeleton is more like that of a simplitied PediceUaster 

 than like that of Asterias or allies. Parenthetically, the mouth-plates of 

 Fedicellaster are more 'prominently 'adambulacral' than those of any 

 genus of the A.steriidie, even of Coscinaslcrias, and are nearly or quite as 

 prominent, relatively, as the oral angles of Uri^iiif/a, In Pedicellaster 

 and Coronaster the ambulacral plates are more ' brisingoid,* unciowded, 

 and the pedicel-pores are in two series, even if later the feet themselves 

 lie in four ranks. In very large si)ecimens of Coronaster the ))edicel- 

 pores form two slightly zig/ag row.-', much less pronounced than in small 

 j-pecimens of Coscinasterias (in the broader sense), and the ambulacralia 

 are less crowded. My own feeling is that, until we arrive at a more 

 satisfastory basis for the subdivision nf the Asteriidte than is now current, 

 it will be much better to leave Coronaster in the Pedicellasteridae." 



