33 



the outer margin of the exopod of the uropods occupies scarcely one-third of the whole margin, 

 and supposing this feature to be correctly drawn we have here an excellent specific character, 

 which shows that A. indicus H. M.-Edw. differs from all the Asiatic forms seen by me and 

 besides from any other species described in the literature, excepting A. americanus Ortmann 

 from the Amazon estuary. The seas south and south-east of Asia evidently contain a good 

 number of species of the genus Acetes; their distribution seems frequently to be somewhat 

 restricted, and I think that A. indicus, taken in a place far distant from any other locality 

 tbr any Acetes seen by me or described by other authors, has never been rediscovered, but 

 ought to be looked for in the Ganges estuary. 



It may be useful here to give a complete list of the species of Acetes hitherto established. 

 In 1859 H. Krüyer published an elaborate representation of a form which he referred to 

 Sergestes and named S: serrulatus Kr. ; he said he had found a couple of specimens among 

 "different Crustacea from the most northern Kattegat". Already in 1896 I pointed out that 5. 

 serrulattis Kr. in reality is an Acetes ; as the Copenhagen Museum possesses one of Kröyer's 

 two specimens I am now able to show that the Museum also possesses specimens from Java 

 and to redescribe the form; that the locality "the most northern Kattegat" is extremely wrong 

 does not require further comment. — In 1893 Ortmann (Ergebnisse der Plankton-Expedition, 

 Decap. und Schizop. Bd. II, G. b., p. 39, Taf. II, Fig. 2) established a species from the Atlantic, 

 A. americamis Ortm., taken in the 'estuary of the Amazon river. — In 1905 Kishinoye (Annota- 

 tiones Zool. Japonensis Vol. IV, pt. 4, p. 163) described and figured a fourth species, A. japo- 

 nicus Kishin., captured at various places in "the western parts of Japan" and in Korea; according 

 to the somewhat imperfect figure of the petasma and for another reason A. japonicus is allied 

 to but distinct from A. dispar n. sp., but whether it may be identical with A. chinensis n. sp., 

 to be described later on cannot be settled, as the male of A. cliinensis n. sp. is unknown, and 

 Kishinoye's description of the female genital area is imperfect and the area not figured. — 

 In 1905 G. Nobili published a preliminary description and in 1906 a more detailed account 

 (Ann. Sci. Natur. Zool. 9. ser., t. IV, p. 23, PI. I, figs. 5- — -^e) of a new species, A. erythrcsns 

 Nobili, from the Red Sea; this species is larger than any seen by me, as the largest males 

 measured 33 mm. in length, and the description together with the rather poor figure of the 

 petasma is probably sufficiënt for recognizing the male. 



In the literature the five species enumerated have been established by five authors, as 

 no writer has seen specimens of more than a single form. Of these five species only one, viz. 

 A. serrulatus Kr., is known to me, but I think that of the four others at least three are 

 recognizable. The "Siboga" has secured two species, both new and tolerably represented, and 

 besides a third form of somewhat doubtful quality. The Copenhagen Museum possesses two new 

 species respectively from the Brazils and La Plata, furthermore from the "Siboga" area and the 

 Gulf of Siam males and females of four species, viz. A. serru/atus Kr., one of "Siboga" forms, and 

 two other species; finally females of at least two species from the seas near China. The result 

 is that I can describe on the following pages no less than seven valid species represented in 

 both sexes, the female of an eighth species, male and female of a species of doubtful quality, 

 and the female of a variety or a new species. 



SIBOGA-EXPEIHTIE XXXVIII. c 



