The first of' these groups was divided into two sub-groups according to the relative length of 

 the ciliated part of the outer margin of the exopod of the uropods, and this character is still 

 vahd. Since 1896 some new species have been established; besides I have seen adult specimens 

 of a good number of species unknown to me twenty-two years ago, and my special study ot 

 the petasma shows that most species must be revised, as there exists some hitherto unrecog- 

 nized forms, and that many of the statements on distribution in the literature are not trust- 

 worthy. Though I have far from finished my intended investigations of the genus Sergestes 

 (and Petalidiuni) ^) I think that a new tabular view of the species of the first group may be 

 useful. But before undertaking this attempt some remarks on the synonymy etc. ought to be 

 made. (On the forms of the second group nothing new can be communicated here, as the 

 "Siboga" gathered only a single species). 



Sergestes tenuiremis Kr. was established on a specimen in the Masfigofi2is-sta.g&. In 1896 

 I stated that a specimen measuring 23 mm. had just acquired the black eyes, but I thought 

 that the adult was unknown. The study of partly new material from the Atlantic yielded the 

 result that S. tentdre^nis must be the Mastigopus of 5. Kroyeri Bate or more probably of 

 S. phor'ciis Faxon, two species which are more closely allied than hitherto supposed. But as it 

 seems to be impossible to decide with absolute certainty whether the Kroyerian larva belongs 

 to S. phorcus or to the other form I propose to drop the name tenuiremis^ at most keeping 

 it as a desisfnation for that elongated larval form. 



Of S. bisjilcatus Wood-Mason I have examined a co-type from the Indian Museum, 

 Calcutta, and three specimens described later on from the "Siboga". All specimens agree on 

 the whole well with Alcock's description. In 1893 Faxon established S. phorcus, but in 1895 

 he referred his specimens "with some doubt" to S. bisulcatus Wood-Mason. Judging not only 

 from the shape of the rostrum as figured by Faxon, but especially from his figure of the 

 petasma his form cannot belong to Wood-Mason's species, and consequently the name 5. phorcus 

 must be re-established. In his "South African Crustacea", Part III, 1905, Stebbing describes and 

 figures a form which agrees excellently with S. phorcus, but not with 5. bisulcatus^ though he 

 follows Faxon in applying the latter name and cancelling 5. phorctis as a synonym. In the 

 material collected by the Prince of Monaco several adult specimens of S. phorcus are found. 



5. prehensilis Bate is closely allied to 5. bisulcatus Wood-Mas., but the eyes are larger 

 with shorter stalks, the antennular peduncles shorter as compared with the squama, and the 

 distal part of their first joint is broader. Besides the petasma of S. prehejisilis Bate differs very 

 considerably from that of S. bisulcatus; Dr. W. T. Calman has kindly examined the petasma 

 in the holotype of 5". prehensilis Bate in the British Museum (Natural History) for me, and 

 according to his figures of the distal half of pars media the processus ventralis tapers from the 

 base to the obtuse end, lobus armatus is not half as long as in S. bisulcatus, with 3 hooks 

 on or near the end, lobus terminalis is thicker with about 7 hooks on the most distal part 01 

 its posterior side, lobus inermis is nearly twice as broad as long and with the end feebly 



l) A paper on the Sergestidje gathered by the French expeditions "Travailleur" and "Talisman" in the Mediterranean and the 

 Atlantic is nearly ready for the press, and at present I work out the Sergestida; collected by the Prince of Monaco in the same seas. 

 Besides I hope later to study a fine material from the Pacific, etc. 



