Trof. P. Martin Duncan — On Galerites = Ecltinoconus. 493 



Echinoconus because of its globular form. He states that it "se 

 distingue nettement de toutes ses congeneres," and he admits that 

 the having five generative plates perforated is a " charactere qui 

 n'avait pas encore ete signale chez les Echinoconus." 



I have placed those details which do not agree with the genus 

 Galerites^EcMnoconifs in italics, and it will be noticed that in nearly 

 all, the structural characters are not those of the typical forms. 



The well-developed and perforated fifth basal plate, the separation 

 of the basals by the radials, and the separation of the posterior plates 

 by the madreporite, are unknown in any other species of the genus. 

 The position of the periproct, situated as it is in the inferior surface 

 of the test and close to the peristome, would not convey the idea of 

 Galerites to any one who has studied the well-known forms of the 

 European Cretaceous rocks. 



The figure given by Cotteau of the structure of the ambulacra 

 does not correspond with that of Galerites ; for, notwithstanding the 

 obliquity of the imperfect triplets, the plates are all low and small 

 primaries, and do not therefore correspond with the interesting 

 character of the ambulacral plates given so truthfully by Loven in the 

 instance of Galerites=^EcJiinoconus albogalerus. 



II. The second species, called Echinoconus Antillensis, Cotteau, and 

 described op. cit. p. 13, figs. 1 and 2, pi. 2, has not the apical system 

 jDreserved, and moreover has an eccentric apex and an oblique 

 peristome ! ! 



Now the question arises, can the first species come within the 

 genus Galerites = Echinoconus ? The reply might take the form 

 of a question, why should the species not be placed in Holecti/jms ? 



The details of the apical system would interfere, but the form is 

 nearer Holectypus than Galerites. With all respect to the opinion 

 of M. Cotteau, I must decline to admit such elasticity in a well- 

 diagnosed genus, and considering that he finds a variety of the first 

 species without any triple pairing, I am bound to believe that the 

 forms are not Echinoconus. 



Loven accepted without reserve the dictum that the forms de- 

 scribed by Cotteau were indubitable Galerites = Echinoconus. He 

 uses this belief in one of his interesting arguments concerning the 

 changes which occur in the apical system and position of the 

 periproct in time. In the work on Pourtalesia, p. 68, Loven writes, 

 "In Echinoconus and Anorthopygtis the vent is posterior, subventral, 

 and the costal (genital-basal) No. 5 is present and without a pore." 



On page 71 Loven writes after considering the Spatangoids : "It 

 has been seen that when in the Echinoconidse the periproct has 

 retreated far back from the calyx (apical system), the costal 5 (that 

 is, the fifth generative plate or basal), which had been suj^pressed, 

 was reinstated again, and that the normal condition returned even so 

 far as to allow the efferent duct of the corresponding sexual gland 

 to perforate it." 



That species vary during time, and that the changes may become 

 so important as to necessitate the introduction of the forms into 

 new genera, can hardly be doubted ; but if the proof is to be 

 scientific, it must be capable of verification from positive facts. 



