cxl BRITISH GEAPTOLITES. 



Gephalograptus, sub-gen. — G. cometa. 

 (b) Dimorphograptus. — I), elongatus, D. Swanstoni. 

 5. Monograptidi. — (Rhabdosome with one row of cells, rarely branched. Hydro- 

 thecae of many kinds.) 



(a) Rhabdosome simple : 



i. Monograptus. — (Hydrothecae of many forms and bent round in a 



distal direction, attached to the axis.) 

 In the group of M. priodon he includes M. priodon mut. Clintoi tenuis 



var. Flemingi, M. galasnsis, M. riccartonensis, M. cuHellus. 

 In the group of M. Bechi,—M. Becbi, M. cygneus, M. scanicus, M. 



Barrandei, M. ctttenuatus. 

 In the group of M. runcinatus, — M. runcinatus, M. dextrorsus, M. 



nodi far. 

 In the group of M. turriculatus, — M. turriculatus, M. proteus, M. 



spiralis, M. triangulatus. In addition he describes M. resurgms 



and M. Clingani. 

 ii. Pristiograptus. — (Hydrothecse, as in Diplograptus, neither elongated 



nor bent round.) 

 In the group of V. freque7is he includes P. frequens, P. dubius, 



P. colonus, P. liocmeri, P. jaculum, P. Hisingeri, P. leptotheca, 



P. uncinatus, P. leintwavdinensis, P. pala. 

 In the group of P. gregarius, — P. gregarius, P. cyphns. 

 In the group of P. testis, — P. testis, and P. discus. 

 iii. Linograptus n. g. — (Like Pristiograptus, but the sicula and hydro- 

 thecse both open distally.) L. Nilssotii, L. concinnus, L. Sauder- 



soni, L. tenuis, L. bohemicus. 

 iv. RastrUes. — (Hydrotheca3 straight, not connected with the axis.) 

 P. Linnsei, P. maximus, P. fugax var. distans, P. peregrinus, 



P. hybridus, R. gemmatus, P. capillaris, H. Barrandei. 



(b) Rhabdosome branched : 



Gyrtograptus. — G. Grayise, (■. Murchisoni, G. rigidus, G. pulchellus, 

 G. Linnarsso7ti, G, Garruthersi. 

 ('). Retiolitidi. — (Rhabdosome with two rows of cells, perisarc consisting of a 

 network of chitinous threads.) 



(a) (Hydrothecae oblique) : 



i. Retiolites. — R. Geinitziauus, P. renosus, P. aitstralis. 

 ii. Stomatograptu? , sub-gen. — S. <j nitidis. 

 iii. Lasicgraptus. — L. bimucronatns, L. costatvs, L. margin itatns. 



(b) Gothograptus, n. g. — -(Hydrothecae vertical.) G. nassa. 



The range and distribution of the Graptolites and dealt with in some detail, and 

 a table is given of their geological distribution. 



