THE APODOUS HOLOTHURIANS 21 



Although many new species of apodous holothurians have been described 

 in the past 20 years, no new genera ascribed to either family have been named, 

 except in the rearrangement of the Synaptidas referred to above. It is remark- 

 able, therefore, that the collection from the National Museum should afford ex- 

 amples of two holothurians so extraordinary that they cannot be placed in any 

 known genus, and the definition of the Molpadiidce will have to be altered to 

 make it possible to enter them in that family. In order to lay out clearly the 

 plan of classification adopted in the present paper, it is necessary to introduce 

 these new genera at this point. The descriptions will be found later on (see 

 pages 39 and 40). One of these genera is based on four specimens from the 

 Western Atlantic Ocean, of which the largest is only 28 mm. long. Owing to 

 some curious lash-like dorsal papillae, I have given the name Himasthlephora 

 to this remarkable holothurian. It bears a striking resemblance to Gephyro- 

 thuria Koehler and Vaney ( :05), which is regarded by its describers as represent- 

 ing a new family (Gephyrothuridfe) of Aspidochirotae. A careful comparison 

 of Himasthlephora with the descriptions and figures of Gephyrothuria convinces 

 me that the two genera are very closely allied, if not identical. But it seems 

 clear to me that they are Molpadiidae and that the new family is quite uncalled 

 for. On account of the differences in the tentacles and the caudal appendage, 

 it seems best to keep the two genera separate for the present. The other genus to 

 be described is based on three specimens from Bering Sea, the general appear- 

 ance of which is not unlike "Trochostoma;" but the tentacles are extraoi'di- 

 narily different, and the name of the genus (Ceraplectana) is based on this 

 character. There are, therefore, eight genera of Molpadiidie recognized in the 

 present report. 



The following table shows in outline the classification herein adopted and 

 the number of species recognized in each genus : 



