HISTORY OF RESEARCH. lxix 



describes and figures a new species of Biplograpsus — (9) B. penna. The genus 



Betiolites he does not consider to be a true Graptolite. He regards Dendro- 



graptus as forming a connecting-link between his true Graptolites (the Rhabdo- 



phora of the later works of Allman and others) and the genera Cattograptus, 



Biclyonema, etc. 



He also treats in brief of the reproduction and development of Graptolites, and 



he concludes that in their mode of reproduction " Graptolites are nearly allied to 



Sertularian Hydrozoa." 



A revision of the genus Bidymograpsus and its British 



jt- j j' species was made by Nicholson in 1870. He groups the 



" On the British species which he assigns to this genus into three sections, 



Species of Didymo- according to the " angle of divergence " ; and he carefully 



grapsus," ' Ann. and distinguishes, therefore, between what he terms the angle of 



Mag. of Nat. Hist.,' divergence and the " radicular angle " of the stipes, and the 

 scr 4 vol v 



position of the cells with reference to the " radicle." 



The distinguishing characters of his three groups are as follows : — 



(a) Radicle on the inferior aspect, and cells on the superior aspect, angle 



of divergence not greater than 180° — B. Murchisoni, I), affinis, B. patulus. (h) 



Radicle as in group (a), but the angle of divergence more than 180° — B. flan- id us 



and B. anceps. (c) Situation of cells reversed, on the inferior aspect, on the same 



side as radicle — B. sextans and B. divaricatus. 



It will be seen from this classification that Nicholson had not yet recognised, 



even to the extent to which Hall had done previously, the systematic difference 



between the true genus Didymograptus and Dicellograptus (Bicranograptus — pars of 



Hall), nor yet the distinction between the sicula proper and its apertural spine. 



The species described and figured by him are (1) Jh patulus ; (2) B. v-fractus ; 



(3) B. extensus ; (4) B. nitidus ; (5) B. affinis; (6) B. serratulus (— B. Nicliolsoni) ; 



(7) B.fasciculatus ; (8) B. gemiuus ; (9) B. bifidus ; (10) B. divaricatus (= Bicello. 



elegans, in part); (11) D. anceps (Bieellograptus) ; (12) B. jfaccidus (Leptograptus) ; 



and (13) B. sextans (Bieellograptus). 



Nicholson followed up this paper by a corresponding 



"Revision of the srenus Climacoqrapsus," of which genus he 

 Nicholson, n „ . , s . _ , . 7 . v , • 



"E 'i f tl C took C. teretiusculus (= C.scalaris or rectangularts) as Ins type. 



Climacograpsus, with His diagnosis is as follows: "Composed of two simple 



Notes on the British unicellular stipes placed back to back, their internal walls 



Species of the Genus," coalescing to form a single vertical septum, along the centre 



'Ann. and Mag. of of ^^ nmg ft delicate solid axis in the f orm f a fibrOUS, 



filiform rod." This rod is always prolonged distally, and 

 generally proximally. Nicholson doubts Hall's statement that in CI. typicalis 

 "there seems to be no septum, but the solid axis runs up the centre of a tub,' 

 common to both series of cellules." He agrees with Hall, however, that the cell 



h 



