56 
THE VOYAGE OF H.M.S. CHALLENGER. 
Genus 7. Embolus, Selenka, 1867. 
Retractor muscles absent. Calcareous ring absent. Tentacles fifteen. Deposits — 
brownish -red ellipses of concentric structure. 
Embolus pauper, Selenka, 1867 ; Pourtales, 1869. 
Habitat. — (?) Cape Palmas (Selenka). 
The genus and species seem to be uncertain. Pourtales says : “ One of the specimens 
sent from the Cambridge Museum to Mr. Selenka had received by some accident 
the label of ‘ Cape Palmas (?) ’ and on this one he has based his new genus 
Embolus. I am perfectly satisfied that the Embolus paib^er, Selenka, is the same 
thing as Molpadia oolitica. The figures he gives of the oesophageal ring of Mol- 
padia oolitica and of a calcareous grain of Embolus pauper are both taken from 
specimens of Molpadia oolitica. The absence of the oesophageal ring in the 
specimen he examined is accidental, as is also the absence of the tail-like 
prolongation of the anal extremity of the body.” Thus, this genus and species 
must probably be omitted. 
In general, the distinguishing characters of the genera of this family are mostly of 
slight importance, and further investigation will probably result in a diminution 
in the number of genera as well as of species. 
