320 PALEONTOLOGY OF NEW YORK. 



the palaeozoic brachiopodous genera " will be found in the character of the 

 pedicle-passage" (p. 161),* its conformation and accessories, has been substan- 

 tiated by all the later investigations of this work,f and is still maintained as 

 the true basis of classification. 



It is not the present purpose to recapitulate at any length the substance of 

 the deductions already set forth in regard to the Inarticulate genera. The 

 views expressed have not been materially modified ; but during the interval 

 since their publication an extraordinary interest has been manifested in the 

 study of the Brachiopoda both recent and fossil, e.specially in France, Austria 

 and America, and the additions thereby made to our knowledge invite special 

 attention. 



LiNGULA has been shown to be a comprehensive type, not existent in pri- 

 mordial faunas. As yet it is impossible to indicate any difference of generic 

 importance between the Lingula of the Lower Silurian and that of existing 

 seas. Its elongate form is not primitive, and its complicated muscular system 

 is indicative of an advanced stage of progress. We may therefore look for 

 the precursors of this type of structure among the less elongate (Lingulella) 

 and more orbicular genera (Obolus, Obolella). In the diagrammatic scheme 

 of the derivation of Lingula, given upon page 164 of Part I, Lingulella and 

 Obolella are represented as divergent from some unknown earlier inceptive 

 stock, whose existence, represented by a mark of interrogation, was deemed 

 probable from the comparative study of these genera. Such an inceptive form 

 would presumptively be wholly elementary in its contour, outline and structure 

 of pedicle-opening, and, in fact, be little more than an amplification of the 

 infantile condition in its descendants. It has since been observed by Beecher 



*lt is pi'Ojier to explain in this place, that ihoug-h Ihe title-page to Volume VIII, Part 1, bears the date 

 of 1892, the i>ag'es relating to the Inarticdlata, including- the concluding chapter referred to, had been 

 completed and printed in ,Iuiy, 1890. Certain of these (pp. 120-lt;0), I'elating to the structure and devel- 

 opment of the peiiicle-passage in Orbiculoidea, Schizookania, Tkematis, etc., were reset and issued sepa- 

 rately at that date, with lithographic plates (IV e aud IV f), and this printed excerpt was distributed 

 among students of the brachiopoda as well as to the general scientific public. 



t The subordinal classification of the Brachiopoda introduced by Waagen (1883-188.5) was based to some 

 extent upon the conformation of the pedicle-passage. The phyletic value of variations in this structure was 

 first clearly indicated by Eugene Deslokgchamps, and has been subsequently elaborated by several 

 writers. 



