ZOOLOGICAL histoid OF CHE BLASTOIDEA. 7 



the Internal and External Structure of Palaeozoic Crinoids" J ; and also by Messrs. 

 Wachsmuth and Springer in the first two portions of their " Revision of the Palseo- 

 erinoidea."- In the year 1881 Montgomery 8 published an account of a new Elceacrinus 



from Canada; and several new American Pentrcmitcs were described by Ilambach 4 , 

 who also published some valuable observations on the structure of tin,' ambulacra. 

 Hut at the same time he revived Say's and White's theory of the passage of tentacles 

 through the pores of the ambulacra ; and he not only totally denied the existence of 

 summit-plates closing the mouth and spiracles, but also asserted that the supposed 

 plates were merely Bryozoa or ovulum-like bodies. These statements were criticised l>\ 

 Dr. P. H. Carpenter 5 ; and in the following year (18S2) we commenced the publication 

 of our joint views respecting the structure and classification of the group 8 . Roemer's 

 terminology was revised and extended, while we proposed two new genera, Pkceno- 

 schisma and Schizoblastus, in accordance with the previous suggestions of Billings and 

 of Meek and Worthen respectively. At the same time, Pentremifidea, Troostocrinus, 

 and Orojj/wcrinus were adopted and more closely defined. In the next year we pub- 

 lished a second series of notes 7 , in which the genus Acentrotremites was proposed 

 for the Mitra elliptica of Cumberland; and various points were noted in the 

 structure of Elceacrinus, Stephanocrinus, Triccelocrinus, and Astrocrinus. Certain 

 new species of extra-British Blastoids were described in both these papers, while 

 the geological and geographical distribution of the genera were set forth for the 

 first time. 



Our nomenclature and revision of the genera were accepted by Mr. Wachsmuth 8 , 

 who published in 1883 some important observations upon the basal plates, and pro- 

 posed the new genus Heteroschisma for some new American species allied to Cadaster ; 

 while new species of Elceacrinus and Pentremitidca were described by Barris 9 . The 



1 Amer. Journ. Sci. 1S77, vol. xiv. pp. 115-127, and 181-191. 



2 Part I., Proc. Acad. Xat. Sci. Philad. 1879 [1880], pt. 3, pp. 226-378, pis. xv.-xvii. ; Part II., Ibid. 

 1881 [1881-82], pta: 2, 3, pp. 177-411, pis. xvii.-xix. 



3 " A Blastoid found in the Devonian Rocks of Ontario." Canad. Nat. 1881, vol. x. pp. 80-84. 



4 " Contribution to the Anatomy of the Genus Pentranites, with description of new Species." Trans. St. 

 Louis Acad. Sci. 1880, vol. iv. no. 1, pp. 145-1G0, pis. A, li. 



5 " On certain Points in the Morphology of the Blastoidea." Ann. & Mag. Xat. Hist. 1S81, vol. viii. 

 pp. 41S-424. 



fi Ibid. 1882, vol. ix. pp. 213-252. 



7 "Further Remarks on the Morphology of the Blastoidea, with Descriptions of a new British Carboni- 

 ferous Genus and some new Devonian Species from Spain." Ibid. 1883, vol. xi. pp. 225-246. 



8 " On a new Genus and Species of Blastoids, with Observations upon the Structure of the Basal Plates 

 in Codasttr and Pentremites." Report Geol. Survey Illinois, l^-vi. vol. vii. pp. .'540-357. Revised in the 

 Proc. Davenport Acad. Xat. Sci. 1885, vol. iv. pp. 76-87. 



9 " Description of some new Blastoids from the Hamilton Group." Report Geol. Survey Illinois, 1SS3, 

 vol. vii. pp. 357-304. Revised in the Proc. Davenport Acad. Xat. Sci. lfeS5, vol. iv. pp. 88-94. 



