REPORT ON THE HOLOTHURIOIDEA. 81 



Habitat.— Station 235. June 4, 1875. Lat. 34° 7' N., long. 138° 0' E. Depth, 

 565 fathoms ; bottom temperature, 3"3° C. ; mud. One specimen. 



On first examining this form, I was surprised to find neither calcareous deposits 

 in the body-wall nor any calcareous ring surrounding the gullet ; besides, the thickness 

 of the perisoma as well as its spongy structure were very striking indeed, and on account 

 of this I at first thought myself justified in founding a new genus. After a renewed 

 examination, however, I was convinced that calcareous deposits as well as the cal- 

 careous ring are really present, though the calcareous substance for some reason or other 

 had been dissolved, most probably by some impurity in the alcohol. By making 

 horizontal sections of the perisoma, and treating them with hematoxylin, the ex- 

 tremely thin sheaths which envelope the deposits become visible ; and by studying the 

 integument most carefully in this manner I have been able to distinguish three forms 

 of deposits closely resembling those in Lcetmogone violacea, which species bears the 

 strongest resemblance to the present one. The genus Cryodora must accordingly be 

 annulled. 



Some of the tentacles are considerably smaller than others. The dorsal processes 

 vary in size, sometimes attaining a length of 25 to 30 mm. and a diameter at the base 

 of about 5 mm. Wherever a process protrudes from the body the perisoma rises, and 

 thus the processes appear as if they ran out from low ridges. The pedicels are 

 especially wide and long. It is impossible to make a detailed examination of the 

 form and the number of the calcareous bodies. The cruciform or star-like deposits 

 (PI. XXXIX. fig. 6) which seem to be the most numerous, present a rather irregular 

 form and measure about 0'22 mm. in diameter ; their arms are rather arcuated and 

 provided with large sjoines. I have not been able to distinguish any small wheels, 

 though they may probably be present ; the wheels which I made out measure about 

 0*24 mm. in diameter (PL XXXIX. fig. 5). 



Traces of a calcareous ring are found in the form of an extremely fine network of 

 minute tubes, the calcareous substance ensheathed by the tubes being now dissolved. 

 The madreporic canal opens externally by ten minute pores, which he close together in 

 the medio-dorsal line immediately in front of the inconsiderable genital process about 20 

 or 23 mm. behind the anterior extremity of the body. The polian vesicle is short, and 

 measures only 15 to 20 mm. The anal termination of the alimentary canal presents 

 only a slight cloacal dilatation. 



The resemblance between this species and the preceding one is most striking, and the 

 only more important character which distinguishes them from one another seems to be 

 the thickness of the perisoma in Lcetmoijone spongiosa ; it is, however, not impossible that 

 the thickness of the integument may depend upon its maceration in impure alcohol, in 

 which case this characteristic peculiarity would also vanish. My opinion is, that until 

 we obtain better material, and are enabled to determine with certainty the form and 



(ZOOL. CHALL. EXP. PART XIII. 1881.) Nil 



