On 26 November 1953 the new research ship Sarsia on her first cruise collected a number of Pontophilus echinulatus (M. Sars) (with an Agassiz trawl, depth 100 fm., La Chapelle, Bay of Biscay). Mr G. R. Forster, of the Plymouth Laboratory, noted that these did not fit into the key given by Kemp (1910) in that they have in the male a distinct appendix interna at the base of the four last pairs of pleopods, while in the female this is absent, the inner ramus being usually undivided, although occasionally an indistinct division can be made out. Otherwise they agree with Kemp's diagnosis.

Kemp (1910) notes M. Sars 1861 as authority, but this is only a preliminary description. In Sars (1868), given in Kemp's (1910) bibliography but not under the species, it is seen that he describes both male and female exactly as in the specimens from Sarsia, the male having a distinct appendix interna on the last four pairs of pleopods and an appendix masculina also on the second pair, the female pleopods having very short inner rami, except in the first which is long, and there is no appendix interna. Sars's figures of these limbs are very good. Kemp (1911) joins Philocheras with Pontophilus, and in this he is now followed by most authors.

Kemp (1916) reviewed the pleopods in the genus Pontophilus, as far as he could with the material he had in India, and he proposed certain groups according to the presence or absence of the appendix interna.