20 Dr. P. H. Carpenter on the 



type form a most essential element in the " monographic " 

 treatment of the subject. In no Invertebrate animals is the 

 relation of the soft to the hard parts more complex than in 

 the Echinoclermata ; and of all the members of this group 

 the Crinoids are those in which the soft and the hard tissues 

 enter into the most intimate relations with one another. 



As this subject has been occupying my attention very 

 closely for the past eleven years, it was with considerable 

 interest that I examined Messrs. Vogt and Yung's anatomical 

 monogra])h on Antedon rosacea, which is the result of their 

 personal investigation of this type ; and I regret to state that 

 I find it to contain a very large number of serious errors, both 

 of omission and of commission, many of which would have 

 been avoided if the authors had taken the trouble to make 

 themselves better acquainted with the literature of the subject. 

 The essential requisite of a work such as theirs, which is 

 intended for the use of students, is the greatest possible accu- 

 racy ; but it is hardly too mucli to say that between misprints, 

 misstatements, and absolute anatomical blunders, there are 

 comparatively few pages of the monograph on Antedon rosacea 

 in which a correction of some kind or other will not be neces- 

 sary before the work is put into the hands of the students for 

 whose use it is intended. 



The authors' inaccuracy and want of acquaintance with tlie 

 literature of their subject appears in two instances at the very 

 commencement of their account of the Crinoidea. They give 

 a definition of the group *, in which the following passage 

 occurs : — " Face orale portant, au centre, la bouche et I'anus 

 dans un espace interradiaire." It has been known, however, 

 for over forty years that there are a large number of Crinoids 

 in which the mouth is not central^ but excentric, or even 

 marginal. Three instances of tliis arrangement were figured 

 by Miiller f in 1849 ; while I have myself frequently alluded 

 to it and have figured several disks \, together with a sec- 

 tional view §, in all of which the markedly excentric position of 

 the mouth is very evident. It has been pointed out again and 

 again during the last eight years that this is the essential 

 character of Mliller's genus Actinometra, and it is given as 

 such in Claus's ' Grundziige.' This genus contains quite one 



* ' TraitiS d'Anatomie Comparee Pratique,' livr. vii. p. 514. 



t " Ueber die Gattuiig Comatula, Lam., und ihre Arten," Abhandl. d. 

 k. Akad. d. Wiss. Berlin, 1849, p. 245. 



\ " On the Genus Actinomefra, Miill., with a Morphological Account 

 of a new Species from the Philippine Islands," Trans. Linn. Soc. 2nd ser. 

 (Zool.), 1879, vol. ii. pl. i. 



§ " The Minute Anatomy of the Brachiate Echinoderms," Quart. Journ. 

 Micr. Sci. n. ser. 1881, vol. xxi. pl. xii. fig. 14. 



