202 



BRITISH GRAPTOLITES. 



Climacograptus caudatus, Lapworth. Plate XXVII, fij 



1876. Climacograptus caudatus, Lapworth, Cat. West Scott. Foss., pi. ii, tig. 48. 



1877. Climacograptus scalaris var. caudatus, Lapworth, Graph Go. Down, p. 138, pi. vi, fig. 34. 



133 a and b. — Civ 

 caudatus, Lapw. 



aogra/ptus 



Polypary 2 — cm. or more in length exclusive of the virgellar prolongation, 

 widening' gradually from its proximal end to a maximum breadth of about 



2—2*5 mm., which is then maintained to the 

 distal extremity. Sicula obscure, virgella 

 1 — 3 cm. or more in length ; virgula con- 

 siderably prolonged. Thecaj twelve to nine 

 in 10 mm., free outer edge curved, slightly 

 inclined. Apertural margin horizontal or in- 

 troverted ; situated in excavations occupying 

 one-fourth the width of the stipe and one- 

 third of its ventral margin. 

 Description. — In the distal region of the polypary 

 the margins are parallel, but proximally they very 

 markedly approximate, the maximum width being 

 attained at a distance of about 2 "5 cm. from the 

 proximal end. The proximal prolongation of the 

 virgella is very striking and characteristic, being 

 1 — 3 cm. or more in length ; close to the polypary it is 

 frequently surrounded by a membranous body with 

 a length of 3 mm. to 1*3 cm.; this is clearly not a 

 part of the true polypary, though it sometimes 

 appears like a prolongation of it; probably the whole 

 sicula was once surrounded by a membrane as in 

 Gl. Wilsoni. The sicula does not appear to be free 

 on either side for any part of its length. 



The septum seems to be complete throughout 

 the entire extent of the polypary. The free outer 

 edges of the distal thecaj in this species are distinctly 

 inclined, and point in the direction of those of 

 Diplograptus. 

 e. Distal C the C8B seen in profile view. Affinities. — Gl. caudatus bears a superficial 



Enlargement of part of specimen resemblance to the Birkhill forms Gl. Tomquisti 



in same slab as 1 1. AXVil, ng. lb. a 



,1. Distaltheca in sub-scaiariform view. aU( i qi me( lius in the long extension of the virgella ; 

 Enlargement ol another specimen ° ° 



...i same slab. from these it may, however, be distinguished by 



a. Proximal end, showing long tube- 

 like virgella surrounded partially 

 by a membrane. Enlargement of 

 part of specimen on same slab as 

 PL XXVII, fig. 7e. 



6. Ditto. Enlargement of part of speci- 

 men on same slab as PL XXVII, 

 fig. 7 b. 



FiGt 



r and d. — Climacotji 

 caudatus, Lapw. 



.,,/., 



