xxx BRITISH GRAPTOLITES. 



increased "inwards inside the tube," and therefore was only discernible in 

 compressed specimens. The thecal walls are noted and entitled sulci 

 obliqui ; but their continuations with the apertures were not observed by him. 

 In addition he notices other structures, which he terms septa longitudinales and 

 transver sales. 



Boeck did not consider that the outer skin had been anywhere provided 

 with opening's, but pointed out that the thickening observable at the base 

 of the thecal walls had somewhat the appearance of such openings. He 

 failed altogether to realise the meaning of his sulci transver sales, which are the 

 edges of the cell apertures. In various cross-sections of the polypary which 

 he examined he recognised the fine thread-like part, tendo (virgula), "to which 

 has been fastened contractile fibres, which could have effected the tube's 

 shortening." 



Affinities. — Boeck admits that practically nothing is known as respects the 



zoological affinities of the Graptolites. He naturally considers, however, that 



their structure, as above described, gives "reason for doubting the prevalent view 



of the time that the once living animals belonged to the family of Polyps, at least 



in so far as they have been placed among the living Sertularia and Pennalula," and 



he suggests that they might be " broken pieces of some tentacularly formed organ 



of a larger animal." 



Harkness in this paper gives a complete list of Graptolites 



_ ' obtained up to that date from the Moffat shales of South 



Har/cness, 



"Description of the Scotland. 



Graptolites found in Twelve species are recorded, of which five are described 



the Black Shales of as new forms. He arranges them under three generic types, 

 Dumfriesshire," 'Quart, adopting the classification of Barrande and M'Coy. 1. Grap- 

 tolites (Monoprion). 2. Diplograpsis (Diprioii). 3. Rastrites. 

 All the species are described and figured. The previously 

 recorded species included (1) Rastrites per egr inns, (2) Gr. Sedgwiclcii, (3) Gr. Bechi, 

 (4) Gr. Nilssoni (not the true Mono. NUssoni, Barrande), (5) Diplog. rectangularis, 

 (6) D. folium, (7) D. foliaceus. Five new species are described by Harkness, viz. 

 (8) Rastrites triangulatus, (9) Gr. Nicoli, (10) Gr. incisus (11) D. nodosus, 

 and (12) IK pennatus, but only the first two are identifiable with certainty at 

 the present day. 



As regards the zoological position of the Graptolites, Harkness considers that 

 the Diprions are " not far removed from Pennatula and Virgularia," possessing in 

 common with them a solid central axis, and a linear arrangement of cells. He 

 asserts that the "existing analogies of Graptolites proper and Rastrites are not so 

 well ascertained ; but on the whole they appear not far removed from the modern 

 genus Sertularia, and partake rather of the character of Hydroid than of Asteroid 

 zoophytes." 



