8 ON THE ECH1NODERMATA OF THE 



With this evidence in view, it is difficult to account for the grounds on which 

 Semper*, after the examination of specimens, grouped the two forms as identical, 

 merging C. Jiorenii, Liitken, into C. Hyndmanni. It consequently follows that his adopted 

 association of P. calcigera, Stimpson, with C. Hyndmanni is equally erroneous. 



Distribution. 



a. Greenland: Godhavn, lat. 69 N. ('Valorous' Exped.); Fiskernsesset (Liitken); 

 Arksut, 15-25 fms., mud bottom (Barrett). 



b. North of American Continent : Assistance Bay, about lat. 74 N., 7-10 fms., 

 muddy bottom (Penny's Exped.), the most northern locality on record ; Labrador, 15 fms., 

 sandy bottom (Packard, fide Verrill) ; Massachusetts ( Verrill). 



Description of the Illustrations of this Species on Plate I. 



Fig. 3. Cwntmaria calcigera : natural size. 



4. Sketch of the mouth-ring and adjacent parts of a young individual : 



magnified. 



5. Generative tubes at an early stage of growth : magnified. 



6. Spicules of the superficial layer in situ : magnified. 



7. Small spicule in profile : magnified. 



8. Disk at the extremity of the sucker-foot : magnified. 



OECULA BAETHII, Troschel. 



1846. Orcula Bartliii, Troschel, Wiegm. Archiv f. Naturgesch. Jahrg. xii. p. 63. 



1857. Orcula Barthii, Liitken, Vid. Meddel. N. Forening i Kjobenhavn, 1857, p. 9. 



1867. Orcula Barthii, Selenka, Zeitschr. f. wiss. Zool. Bd. xvii. p. 352. 



1868. Orcula Barthii, Semper, Eeisen im Archipel der Philippinen, Holothurien, pp. 68, 274. 



Dr. Liitken, in describing some Greenland examples of this Holothurian, states f 

 that they present a regular sausage form, with a length (in one which seemed to 

 have best preserved its natural proportions) of 3 inches and a thickness of over f inch. 

 The body-skin is brownish in colour, but almost concealed by the numerous bluish or 

 whitish sucker-feet with which the whole body is closely crowded. Neither in the 

 skin, which is thick and tough, nor in the feet is there any trace of solid calcareous 

 formations. A thick layer of transverse muscles lies under the outer skin ; and also 

 five strong longitudinal bands, each of which gives off, at a distance from the anterior 

 extremity equal to about one third the entire length of the animal, a short thick 

 muscular bundle, which is attached to one of the radial elements of the ocsophageal 

 ring, whilst the main bands themselves are continued up to the anterior extremity of 

 the body, and are then inclined backwards again, running as five thin narrow bands 

 along the outer wall of the inverted oesophagus until they reach the points of the 



* Eeisen im Archipcl der Philippinen, Holothurien, p. 237. 



t The present writers having unfortunately had no opportunity of examining this Holothuroid, have 

 accordingly availed themselves of giving the ahove translation of the observations made upon the form by 

 Dr. Chr. Liitken, the eminent and accurate Danish zoologist, in the memoir ahove quoted. 



