132 



MR. H. LAP WORTH ON THE 



[Feb. 1900. 



a b c 



-- obverse aspect ; 6=reverse 

 aspect. 



-The same ( x5). 



apparent length. The primary theca appears to have grown slightly 

 below the aperture of the sicula. The virgella is produced from y L 



to -^ inch beyond the proximal 

 Fig. 20 a. — Climacograptus par- end" of the sicula. 



yulus, sp. nov. (nat. size). In the reverse aspect a small 



fraction of the aperture of the 

 sicula is always seen projecting 

 below the first theca of the 

 secondary series. An impressed 

 septal furrow seems to be pre- 

 sent, commencing between the 

 first and second thecae of the 

 primary series. 



There can be little doubt as 

 to the justifiability of the sepa- 

 ration of this minute form as a 

 distinct species. It occurs only 

 on one horizon in the Rhayader 

 district, where it forms the 

 commonest fossil; and it never 

 varies to any extent from the 

 above dimensions. 



This form bears a superficial 

 resemblance to CHmacoc/raptus 

 minutus, Carr., but differs from 

 it 



(1) In size, being smaller and proportionately broader; 



(2) In the deeper excavations above the tbecal apertures ; and 



(3) In having an extension of the virgella, and no prolongation of the 



virgula. 



Horizon. — DyfTryn Flags, Gwastaden Series, in the lihayader 

 District, in conjunction with Diplotjraptus acuminatus, Nich. 



JJiplogsaptus magnus, sp. nov. (Fig. 21 a-d, p. 133.) 



Mature rhabdosoma. — The rhabdosoma reaches a length of 

 at least lif inches. Commencing with a more or less pointed 

 proximal end, it increases in width gradually and uniformly to about 

 one-half or rive-eighths of its whole length from the proximal end. 

 Here it attains its maximum width ; from this point upward it 

 graduall)' decreases, and at the distal end its breadth is only about 

 rive-sixths of the maximum. The average measurements are as 

 follows : — 



Width at the top of the 2nd thecse (prim.) 



10th ,, 

 Maximum width at five-eighths of the 



length from the proximal end 



Width at the distal end 



Inch 

 =0U4 

 =0-10 



=017 

 =015 



The thecae vary greatly in their size and inclination : at the 

 proximal end they number from 33 to 31 in the inch, with a length 

 of 3 to 4 times their breadth, and inclined at about 37° to the 



