502 J. Hopkinson — Oyi New British Ovaptolites. 



who has recently added greatly to our knowledge of the succession 

 of the Cambrian and Silurian rocks of these southern uplands of 

 Scotland, and who, I believe, will soon add several additional species to 

 those here described. The first two species described do not belong to 

 the Graptolitidae proper, but are here included as nearly allied forms. 



Class, Hydrozoa. 

 Order, Hydkoida. Snb-order, Atheoata ? Family, Corynoidea. 

 1. Corynoides gracilis, sp. nov, — PL XII., Fig. 1. 

 Polypary from about five-eighths to three-quarters of an inch in 

 length, and about l-50th of an inch in average breadth, gradually 

 expanding from the proximal to the distal end, where there is a 

 slight bulbous expansion terminating in short acutely-pointed teeth. 

 Commencing with two slender radicular processes which lie so 

 close together that they are scarcely individually perceptible, the 

 polypary, liere not 1-lOOth of an inch in breadth, gradually enlarges 

 until a breadth of nearly l-30th of an inch is attained. Up to this 

 point the margins of the polypary are almost perfectly straight, but 

 here there is a slight enlargement, which, in G. calicularis (Nich.), 

 has been described as a "cup-like hydrotheca." This portion of the 

 polypary is about l-20th of an inch in length, and scarcely l-20th 

 in breadth at its widest part. It is convex in form, and terminates 

 distally in about five acutely-pointed teeth, which at first sight 

 appear to form the greater part of this so-called hydrotheca. But 

 this appearance is caused by several fibres, somewhat resembling 

 the virgula of the typical graptolites, which traverse the polypary 

 throughout its length, and form the extreme distal termination of 

 each of these segments, which are really connected together to 

 within a very short distance of their apices. These fibres, whatever 

 their nature may be, apparently form a framework which supports 

 the less rigid and more membranous portion of the polypary, as 

 the frame of an umbrella supports its cover. 



This species differs from C. calicularis, the only one hitherto described, in its 

 greater length and tenuity, and in the form of its expanded portion. 



The systematic position of the genus Corynoides is very doubtful. Prof. Nicholson, 

 its original describer, considers it to be "closely analogous to the Corynidce or 

 TubulwridcB of our own seas, especially resembling such forms as Oorymorpha, in 

 which there is but a single polypite. It cannot, however," he adds, "be considered 

 to be absolutely referable to the Corynidce, since no known Corynid exists as an 

 independent or free-floating organism, such as Corynoides seems undoubtedly to have 

 been." ^ 



Whatever its mode of existence may have been, Corynoides could not belong to the 

 Oorynidffi, or Athecata, if it possessed a true hydrotheca. In some of the Athecata, 

 however, the polypites are partially, and in one species at least, wholly retractile into 

 •the distal extremity of the polypary. I refer to such forms as Atractylis arenosa, and 

 several species of Perigonimus. The polypite of Corynoides has very probably been 

 similarly retractile, and as its non-contractile polypary would seem to preclude the 

 idea of its having floated freely in the old Silurian seas, I consider that in the present 

 state of our knowledge we cannot do other than place it provisionally amongst the 

 Athecate Hydroida. At the same time I must admit that the absence of any hy- 

 drorhiza apparently capable of attachment to foreign bodies, in the true graptolites, as 

 well as in the Corynoidea, renders it improbable that they resembled, in their mode of 

 existence, the fixed Hydroida of our present seas. 

 Loc. Llcmdeilo : — Lochan Burn, Queensberry Hill, Dumfriesshire. 



1 Geol. Mag., Vol. IV., p. 108. 



