lviii BRITISH GRAPTOLITES. 



In 1867 Carrutliers criticised Nicholson's views respecting 



Carruthers ^ ie so " ca ^ e<: ^ " Grapto-gonophores." He denies their ovarian 



" Note on the Syste- character, believing them to be Brachiopods, i.e. Siphonotreta 



matic Position, etc., micula, etc. He thinks that the supposed attachment is only 



of Graptolites," a case f accidental juxtaposition, as it would be more natural 



for them to be attached by the mucro end, and he draws 



attention to the fact that no living Hydrozoon has " corneous " gonophores that 



become free swimming zooids. Moreover, no scars of attachment have been 



observed. Nor, he points out, do they bear any resemblance to the young 



Graptolite forms figured by Hall, the various stages of growth of which Carruthers 



himself had traced in the development of his own Diplog. triromis. 



As regards the affinities of the Graptolites themselves, Carruthers now 

 inclines to the opinion that " although they resemble the Hydrozoa in general 

 aspect, they are nevertheless more closely allied to the Polyzoa in the following 

 characters : 



1. There is no distinct common canal. Sometimes the polyps rise from a 

 common substance which extends along the whole of the celluliferous portion of 

 the organism, but there is no constriction or septum at the base of the cells. In 

 other species the Avails of the cells are continued to the solid axis. 



2. The mouths of the cells are furnished with spines. 



Graptolites, however, differ from all living zoophytes in possessing — (1) a solid 

 axis, (2) free polypidoms. 



In this paper Carruthers places his species Cladograptus linearis in the genus 



Dendrograptus. 



The same year Nicholson described some Graptolites from 



, T . , , ' the Lower Silurian beds of the South of Scotland, including 



Mictiolson, ° 



" On some Fossils from three which were new to science, viz. (1) Diplog. tubulari- 

 the Lower Silurian formis, (2) I), acuminatus, (3) Didymog. anceps ; and three 



Rocks of the South of species named by earlier observers — (4) Didymog. flaccidus, 

 Scotland," 'Geol.Mag.,' ^ m . p i og> qua drimucronatus, (6) !>. WHtfieldi. 'lie also 

 describes a new genus, Corynoides, typified by the species 

 (7) C. calicularis. As regards this genus, the name of which was suggested by 

 Harkness, Nicholson defines it as a " simple hollow tube, probably corneous, 

 provided with a single or double radicle or mucro, and developed distally into a 

 cup-like hydrotheca." The single polypite is " closely analogous to some of the 

 Corynidas or Tubularidge," especially resembling Coryomorpha. He holds that it 

 was " undoubtedly a free floating and independent organism." 



In the same paper Nicholson also describes and figures three types of Hall's 

 " germs " of Graptolites, belonging apparently to " Diplog. pristis." He figures 

 three stages of growth in this form, also the early stage of a- uniserial species. 



In this last example it will be seen that the true sicula is well represented as 



