ME, P. H. CAEPENTER ON THE GENUS ACTINOMETRA. 73 



described by Goldfuss \ of which neither be nor any subsequent observer bas given a 

 satisfactory explanation 2 . 



Glenotremites was at first placed by Goldfuss among the Echinoidea, and was sup- 

 posed by him to have some relationship with the Cidaridcs. It is a somewhat hemi- 

 spherical body, in the centre of the flattened upper surface of which is a large round 

 opening, called by Goldfuss the mouth. " Um den Mund liegen fiinf grosse ovale Locher 

 and zwischen diesen fiinf fiaehe Einnen, die sich bis zum llande erstrecken, wo ihre 



Vertiefung nicht auslauft, sondern durch einen erhabenen Saum begriinzt wird 



Die Locher gehen trichterformig in die Tiefe ; die Einnen sind die Felder der Fiihler- 

 gange." These grooves were supposed by Goldfuss to be perforated by minute pores for 

 the passage of tentacles. 



The convex dorsal side of the body bears numerous sockets for the attachment of 

 cirrhi ; but Goldfuss compared these at first to the large tubercles of the Cidaridte. At 

 the apex are five smaller apertures ; and Goldfuss suggested that these might be respi- 

 ratory and the others genital, or, more probably, that both, like the cirrhus-sockets, 

 marked the points of attachment of various kinds of spines. Subsequently, however, in 

 his description of a second species, G. conoideus, he spoke of the larger apertures as 

 ovarian openings, and recognized the resemblance between the sockets on the convex 

 surface and the similar ones on the dorsal surface of the centrodorsal piece of Comatula 

 to which the cirrhi are articulated ; and he suggested that Glenotremites might be more 

 nearly related to the Comatulidee than to the JEchinidce, as he had at first thought. 

 Agassiz 3 adopted this view, and placed Glenotremites among the Crinoids, and near to 

 Comatula. Like Goldfuss, he regarded the central aperture as a mouth; but the five 

 punctated grooves radiating from it, which were supposed by Goldfuss to be provided 

 with tentacles, were regarded by Agassiz as the points of insertion of the radii. He did 

 not attempt to explain the five large openings on the ventral surface and the five smaller 

 apical ones. Reenter 4 , who, like all subsequent writers, accepted the view that 

 Glenotremites is the centrodorsal piece of a Crinoid allied to Comatula, regarded the 

 former as " trichterformigen Arm-Anfangen oder Mund-Winkeln," but did not under- 

 stand those of the dorsal surface. 



D'Orbigny 5 , who confused Glenotremites with Comaster and Solanocrinus under one 

 name, Comatula, and Pictet 6 , who retained it as a separate genus, did not attempt to 

 offer any further explanation of its peculiarities, and, so far as I know, Agassiz and 

 R center's views have been generally accepted. 



1 Petref. German, i. p. 151), Taf. xlix. fig. 9, Taf. li. fig. 1, and ii. p. ISO, Taf. clx. fig. 18. 



2 The following section was written early in 1877, and was in the hands of the Secretary of the Linnean Society 

 in June of that year. The substance of a portion of it was referred to in my paper on Pentacrintts and Rhizocrirms 

 ('Journal of Anatomy and Physiology,' Oct. 1S77, p. 45). I am therefore exceedingly glad to find, from a paper 

 published early in 1878 (" TJeber einigc astylide Crinoiden," Zeitschrift der deutsehen geologischeu Gesellschaf t, Jahr- 

 gang 187S, p. 33), that Schluter has independently given the same explanation of Glenotremites as had occurred to 

 myself. I learn from his paper that even as late as 1871 Goldfuss's original views were still held by Geinitz (Elb- 

 thalgebirge, i. 1871, p. 91). 



3 Prodrome, Joe. cit. p. 289. 4 Lethaja Geognostica, v. p. 177. 



6 Cours elementaire, ii. p. 138. c Traite de Pale'ontologie, iv. p. 290. 



