24 The Ottawa Naturalist. [May 



We may grant this so far as very common species are concerned, 

 and for most specimens taken from below the present rock sur- 

 face. There are two fields, however, in which the loss is not 

 only real but at the same time serious. I refer here to weathered 

 surface material and to rarer species whose structure is not 

 fully known. 



Well weathered material may in a single specimen reveal 

 many minute details, both of outer surface and interior. If 

 the nearly complete form is preserved, such a specimen may be 

 saved, and finally yield new truths to some paleobiologist. 

 On the other hand any great loss of surface or of other portions 

 of the whole may make the specimen one of little or no value to a 

 collector of the second type, yet the fragment might show de- 

 tails of inestimable value to the collector of the third type. We 

 must elaborate these statements somewhat in order to get a 

 clearer idea of their import. 



A complete specimen may do no more than add a new species 

 to our ever growing lists, while a well weathered fragment may 

 add largely to our knowledge of the structure and function of a 

 whole order. For example, the type of Blastoidocrinus car- 

 charidens Billings, shows less than half of a complete specimen, 

 but it reveals the character of its food-grooves; cover-plates; 

 floor-plates ; the drainage tubes situated between the outer ends 

 of the latter and leading into the hydrospires; the outer sur- 

 faces of the hydrospire folds ; the exceeding thinness of the latter, 

 fitting the organ to perform the function of respiration ; the fine 

 corrugations on their inner surfaces, giving strength" with ex- 

 treme lightness; the external openings or discharge pores, show- 

 ing the direction of flow to be downward (cataspires), and not 

 upward (anaspires) as in the blastoidea; and the true basals. 

 (See N. Y. State Museum Bulletin 149, plates I-IV.) Not one 

 of these things was to be seen in the well-nigh perfect specimen 

 collected by E. M. Hudson on Valcour Island, until it was sec- 

 tioned, and even then the details shown were neither so numerous 

 nor so complete as in the holotype, and in other still smaller 

 fragments. (N.Y. State Museum Bulletin 107, plates 1-4). The 

 holotype also demonstrates the absence of a lancet plate, and 

 is itself clearly an example of a new order of Echinoderms, the 

 Parablastoidea (last reference, page 119). 



Let me refer to another specimen less than " half there." 

 This is the type of Protopalaeaster narrawayi, papers on 

 which appeared in The Ottawa Naturalist in May, June, 

 July and December, 1912, and October, 1913. In addition 

 to these papers the species was figured in N.Y. State Museum 

 Bulletin 164; bv W. K. Spencer, in part I of his "Monograph 

 of the Paleozoic Asteroidea," 1914; and further shown by a 



