24 Dr. P. H. Carpenter 07i the 



life ? Would Messrs. Vogt and Yung figure a vertical section 

 of Pentacrinus or Rliizocrimis with its mouth downwards 

 and its stem " en I'air " ? 



Another illustration of the authors^ want of acquaintance 

 with the recent Crinoid literature which has not emanated 

 from the pen of Professor Perrier is afforded by the following 

 passage on p. 571 : — 



" Les Comatulides libres (Antedon, Acftnometra) oflFrent 

 fort peu de differences anatomiques, et sauf quelques details 

 insignifiants, sont construites absolument sur le meme plan 

 que notre esp^ce type." 



My comments on this passage shall be put in the form of a 

 series of questions. 



1 . Is it a " detail insignifiant " that more than half the 

 arms, with the majority of the pinnules in some forms of 

 Actmometra, have neither ambulacral groove, tentacles, nor 

 ventral nerve? This fact was first published in 1876, and 

 has been since noticed over and over again in papers on 

 Crinoids which are included in the bibliography given by 

 Messrs. Vogt and Yung. 



2. Is it a " detail insignifiant " that the sacculi which 

 Messrs. Vogt and Yung describe as parasitic " zooxanthelles " 

 are never found in the exocyclic Actinometray even when 

 living side by side with Antedon in the same locality, though 

 they occur in three other endocyclic Coraatula3 ? 



'6. Is it a " detail insignifiant " that the arms and pinnules 

 of many species of Antedon are provided with a very well- 

 defined ambulacral skeleton, consisting of a double row of 

 side plates and covering plates, the former being notched for 

 the reception of the symbiotic "zooxanthelles;" but that 

 side plates and covering plates are entirely absent on the arms 

 and pinnules of Actmo7nefra, even in species which have a 

 strongly plated disk? These characters were described in 

 1880 and 1882 respectively. 



4. Is it a " detail insignifiant " that the mouth of Actmo- 

 metra is excentric, and that its alimentary canal makes four 

 coils round the disk instead of one only, as is the case in all 

 the endocyclic Crinoids ? 



A diagram of this arrangement was given in the Report 

 on the ' Challenger ' Crinoidea, which appeared early in the 

 year 1885, and formed the subject of an article by M. P. de 

 Loriol in the ' Archives des Sciences physiques et naturelles,' 

 published in the following April at Geneva, the very town in 

 which Messrs. Vogt and Yung are professionally engaged ; 

 while a second notice of the report was given by Professor 

 Perrier in the ' Eevue Scientifique ' for May 1885. 



