REPORT ON THE HOLOTHURJOIDEA. 91 



always rather depressed. The perisonia along the sides of the body, as well as round its 

 anterior and posterior extremities, thick, forming a continuous more or less thin border or 

 brim, the breadth of which is very considerable anteriorly. Tentacles from ten to 

 twenty. Mouth completely ventral, at a considerable distance from the anterior extremity 

 of the body. Round the edge of the brim there is a single row of numerous, commonly 

 minute pedicels, often resembling protuberances or wart-Like prominences ; the foremost 

 of those prominences belonging to the dorsal ambulacra, the rest to the ventral lateral ones. 

 The odd ambulacrum generally with a double row of minute retractile pedicels ; in one 

 form naked. The dorsal surface naked (?) or with a few minute processes ; or with a 

 greater or smaller number of commonly minute but sometimes rather large, retractile or 

 non-retractile processes, disposed in a single or a double row along each ambulacrum ; or 

 with a great many minute, completely retractile processes, scattered over the lateral 

 interambulacra ; or with fewer pairs of small, non-retractile processes anteriorly and 

 a very large appendage, crossing the odd interambulacrum at a greater or smaller 

 distance from the posterior extremity of the body. Calcareous deposits : spicula or four- 

 armed, cruciform bodies. Calcareous ring incompletely developed, composed of five 

 separate pieces (?), each consisting of a very fragile network. 



The presence of pedicels along the three ambulacra of the ventral surface is to 

 be regarded as a very valuable character for this family. A single genus, Psyehcotreplies, 

 forms an exception to this rule by having its odd ambulacrum naked. Considering this 

 peculiarity, as well as the number of tentacles, it seems as if this genus may be considered 

 as a transitional form connecting the family in question with the Elpidiidse ; consequently 

 it remains to be decided to which of these two families it ouoht to be referred. The 

 presence of the brim round the flat body has decided me in classing the animal in 

 question in the family Psychropotidse. 



The remarkable large azygous appendage which gives the genera Euphronides and 

 Psychropotes such a peculiar appearance is completely wanting in Benthodytes, which by 

 its exterior seems to approach the representatives of the family Asjtidochirotse. On 

 a closer examination it becomes evident that Euphron ides and Psychropotes are closely 

 allied, and more than once I have hesitated whether they ought to be considered as be- 

 longing to one and the same genus or not. The former is characterised by its very 

 depressed body, which almost reminds one of gigantic Planarians ; besides, its append- 

 age is considerably smaller in comparison with the size of the body than is the 

 case in Psychropotes, and is situated comparatively far from the posterior extremity 

 of the body. The genus Psychropotes on the other hand has its body almost without 

 exception rather high posteriorly and depressed anteriorly, and its gigantic appendage, 

 being situated close to the posterior extremity of the body, bears a strong resemblance 

 to a tail. 



