52 Annals of the South African Museum. 



., (Finger of first gnathopod diminutive 3. Arcturus. 



| Finger of first gnathopod well developed 4. 



. \ Side-plates of second to seventh perseon segments distinct . . 4. Antarcturus. 



I Side-plates of person segments not distinct 5. Pleuroprion. 



Cordiner's work, to which the premier genus of the family is due, 

 was published in numbers, unpaged, " without any regard to order or 

 connection." The plate of Astacillce, &c., bears the date, " Pub- 

 lished Dec r . 28, 1793 by Peter Mazell Engraver No. 32 Bridges 

 Street Covent Garden." An introductory address, signed by Charles 

 Cordiner and Peter Mazell, is dated July 1, 1788. An editorial 

 "Order of Publication. New arrangement," gives 24 numbers, 

 placing the Astacillce in No. xxi. 



GEN. ANTAECTUEUS, zur Strassen. 



1902. Antarcturus, zur Strassen, Zoologischer Anzeiger, vol. xxv., 



p. 686. 



1903. Antarcturus, zur Strassen, in Chun, Aus den Tiefen des 



Weltmeeres, ed. 2, pp. 189, 561. 



With regard to the distribution of the genus Arcturus in the un- 

 restricted sense, zur Strassen observed that only in the cooler seas 

 did its representatives ascend to the surface waters, and further, that 

 a zone of the globe between 20 and 50 of northern latitude was 

 quite without examples of this otherwise ubiquitous genus. Upon 

 closer examination he convinced himself that the group of species 

 living north of the empty zone was generically distinct from the 

 group to the south of it. Accordingly with the type species Arcturus 

 baffini (Sabine) he placed A. tuberosus, Sars, A. longis])inis, Benedict, 

 A. glabrus, Benedict, A. beringanus, Benedict, and with slightly less 

 certainty Arcturus hystrix, Sars, A. murdochi, Benedict, A. inter- 

 medius, Eichardson. For the southern species he established 

 Antarcturus and Antares, in the following year changing the latter 

 name, which was preoccupied, into Pleuroprion, to which Miss 

 Eichardson, in 1905, transfers A. hystrix, A. murdochi, and A. inter- 

 medium. In Antarcturus the first perseon segment is not produced 

 downward and forward to cover the mouth-organs and base of the 

 first gnathopods ; the finger of the first gnathopods is strongly 

 developed, and these limbs themselves are fairly robust ; the three 

 following pairs of limbs are laterally prominent and geniculate. 



These characters given by zur Strassen should, no doubt, be rein- 

 forced by the addition that the marsupium is composed of four pairs 

 of plates, since the type species .1. oryx is said to stand very near to 



