REPORT ON THE HOLOTHURIOIDEA. 41 



resemble a network, and comparatively large, about 0'14 mm. in diameter ; they are very 

 Scattered, and consequently difficult to detect ; every here and there in the integument of 

 the body some larger, straight and more spinose spicula are to be observed. The pro- 

 cesses, the pedicels, and the tentacles contain a number of smooth, spinose, rather large, 

 more or less fusiform, or slightly curved spicula. 



According to my observations, each of the five pieces of the calcareous ring consists of a 

 central part, from which issue in opposite directions ten rods, five towards each side ; their 

 terminal part is flattened and expanded. From want of material I have not been able 

 to give any figure of the ring. The polian vesicle seems to be inconsiderable. The niadre- 

 poric canal appears to be destitute of deposits and opens externally a little in front of 

 the dorsal processes. The posterior part of the alimentary canal dilates into a large 

 cloaca, which runs out from the left side into a considerable prolongation, directed 

 forwards. In regard to the number of the ambulacra! canals of the water-vascular system, 

 which I have found to be five in all forms of the order Elasipoda, but which Daniels- 

 sen and Koren state in the species Kolga hyalina to be only two, I refer to the anatomi- 

 cal part of my report. All along each side of the ventral surface are to be seen some 

 small globular vesicles attached to the nerve-cords; these measure about 0"14 mm. in 

 diameter and are disposed one at each nerve-branch which is given off to the pedicels, 

 two a little before the first pair of pedicels, and two between the first and the second 

 pair of pedicels. Several such auditory vesicles are doubtless to be found on the nerve- 

 ring, though from want of material they have escaped me ; as in Elpidia glacialis and 

 several other species, their position seems to vary a little. They are fined interna 11)- 

 by a layer of large cells, and contain up to twenty minute, oblong otoliths (PI. XXXVI. 

 fig. 25), measuring about 0"028 mm. in length, then* wider end being rounded and 

 the opposite one truncated. The reproductive organ consists of a fascicle composed of 

 two bundles of small CEeca ; the organ opens immediately behind the pore of the madre- 

 porie canal. 



When comparing the above-described species and that of Danielssen and Koren with 

 one another, one finds that the latter is distinguished by the following characters : — 

 The processes of the dorsal surface, six in number, project from a continuous, trans- 

 verse, slightly curved ridge ; the mouth is ventral and the number of pedicels varies 

 from fourteen to eighteen ; besides smaller and larger, unbranched and arcuated 

 spicula, resembling those of Kolga nana, there are also to be discovered rather large 

 and branched ones, and, though exclusively in the oral disk, some small rosette-shaped 

 bodies together with some net-like perforated plates ; each of the five pieces con- 

 stituting the calcareous ring gives off fourteen rods, seven towards each opposite side, 

 four of which are always longitudinally split ; the auditory vesicles are twenty-six in 

 number, and the otoliths of each auditory vesicle vary from about twenty to one hunched 

 and thirty. 



(ZOOL. CHALL. EXP. PART XIII. 1881.) N 6 



