REPORT ON THE HOLOTHURIOIDEA. 141 



fig. 5, a), while those of the pedicels having an elongated shape and being directed 

 towards the middle line of the ventral surface are remarkable in that their Wind end 

 is slightly expanded and terminates in numerous, ten or more, csecal branches. As 

 above stated, the processes in Pannychia communicate with small branched vesicles, 

 while the pedicels are provided with elongated ambulacral cavities. 



The genus Lcetmogone amongst the Deimatidae (PI. XLII. figs. 2 and 7), as well as most 

 of the representatives of the Elpidiidee (PI. XLII. fig. 5, c, and PL XXXVI. figs. 5 and 6), 

 are provided with unbranched ambulacral cavities, the form and appearance of which have 

 already been demonstrated in the description of the species. The cavities, especially those 

 belonging to the pedicels, seem in general to become elongated and tapered towards their 

 cgecal end, which lies more or less close to the medio-ventral line, while their opposite por- 

 tion, from which the pedicels proceed, often attains a considerable width; sometimes, as in 

 Lcetmogone violacea, Scotoplanes globosa, Elpidia glacialis, &c, this portion is so broad 

 and wide that the cavities of the different pedicels become closely crowded side by side and 

 separated from one another by a thin wall only (PL XLII. fig. 2, and PL XXXVI. fig. 5). 



In the two known species of Deima a canal system is present which, as far as I know, 

 does not exist in any other Holothurid. As may be remembered these two forms carry a 

 great number of minute papillae arranged in a single crown round the anterior aperture 

 of the body (PL XLIII. fig. 2, a, and fig. 5, a), inside which the tentacles are situated. 

 These papillae, which are strengthened by small branched and perforated, irregular 

 calcareous deposits, are in communication with fine canals (PL XLIII. fig. 5, d), which 

 lie closely crowded side by side and are intimately united with one another, thus forming 

 a continuous whole which closely surrounds the tentacular cavities. The canals being 

 directed outwards and backwards, it has been possible to follow them as far as the 

 neighbourhood of the most anterior part of the radial ambulacral vessels. The walls of 

 the canals are made up of longitudinal fibres, and are supported by small, branched, 

 scattered calcareous spicules. Along each of the canals a distinct nerve-branch is visible. 

 There is no doubt that this system of canals is connected with the ambulacral system, 

 and in Deima validum it appeared to me that this communication takes place just 

 where the radial ambulacral vessels begin. 



In some Elasipoda, as, for instance, in Ilyodoemon maculatus, See. (PL XLII. fig. 3, c), 

 laro-er or smaller cavities are present in the more or less thick perisoma, which cavities 

 should be regarded as belonging to the water-vascular system. The walls of the 

 ambulacral system frequently contain a varying quantity of calcareous deposits. 



The Reproductive Organs. 

 In all the Elasipoda, without any known exceptions, the sexes are distinct, as is the 

 case in the majority of the other Holothurioidea. Generally, the reproductive organs 

 arc more or less bilaterally symmetrical, consisting of two fascicles of longer or shorter. 



