ARCTIC SEA TO THE WEST OF GEEENLAND. 7 



The reproductive organs consist of simple tubes. A figure is given of their condi- 

 tion in an early stage of growth (Plate I, Fig. 5). 



The calcareous plates and spicules which indurate the integument are highly cha- 

 racteristic. As previously stated, they are so closely placed as to imbricate upon one 

 another; and it is consequently very difficult to determine the form of individual pieces 

 until separated by treatment in caustic potash. The plates which form the outermost 

 layer vary in shape from roundish to oblong, and even irregularly stellate forms, their 

 greatest diameter ranging from 0'28 to 0'35 millim. (Liitken). They are perforated with 

 closely-placed holes, whose distance apart is less than their diameter, no plan being 

 discernible in their arrangement. From the centre of each rises a subconical elevation, 

 made up of fine calcareous rods, about one third as high as the diameter of the plate, 

 and which terminates with two or three spikelets. It is to these spicular plates that 

 the rough texture of the skin is due, and the granular appearance it presents when 

 examined with a hand-magnifier of low power. 



Underlying the plates just described is another layer of oblong and much narrower 

 plates, also closely packed together and overlapping, and which are present in greater 

 number over a given area in consequence of their smaller size. These pieces are generally 

 punctured with two (or sometimes three) rows of holes, which become smaller in 

 diameter towards the extremities of the plate. 



The skin of the sucker-feet is comparatively as densely plated as that of the body, 

 the spicules at the base being similar in character to those above described, but smaller 

 in size ; towards the extremity, however, they become much narrower, bear fewer holes, 

 and are somewhat more curved, whilst mixed up with them may be found a number 

 of quite rudimentary plates. When the great number of these scales and the method 

 of their arrangement are borne in mind, the reason of the suckers being incapable of 

 retraction becomes at once self-evident, as well as that of the small size of the internal 

 ampullae, which follows as a correlative result. The calcareous disk at the extremity of 

 the sucker is well developed and very characteristic. It is a delicately fine circular 

 network, having the immediate centre occupied with a number of small round holes, the 

 rest of the piece being characterized by large subhexagonal apertures, which diminish 

 in size as they approach the margin. 



Respecting the affinities of C. calcigera, it may be said that although the form bears 

 undoubted resemblance to Cucumaria Hyndmanni, Thomson, this is in external appear- 

 ance only, as has been already pointed out by Diiben and Koren*; whilst Liitken f, in 

 his description of C. Korenii, specified in detail the differences which exist between the 

 two species. As a fact, the calcareous plates are altogether different in C. Ilyndmanni 

 being alike and constant in form, whilst in C. Korenii (C. calcigera) there are not 

 only two layers of quite distinct kinds, but the plates themselves vary very considerably. 

 The plates also of the sucker-feet are broader, perforated with more holes, and are less 

 regular and less uniform than in C. Hyndmanni ; and, lastly, the fully-developed disk at 

 the extremity of the sucker is characteristic of the present species. 



* Kongl. Vetensk. Akad. Handl. ar 1844, p. 299. 



t Videnskabelige Meddelelser f. d. Naturh. Forening i Kjobenhavn 1857 p. 6. 



