68 



Two new forms were obtained by the Siboga Expedition, Scyll. gibberosus from the 

 sea between Misool and New Guinea and Scyll. bicuspidatus from the Strait between Sumbawa 

 and Flores : with the former Scyll. Nobilii (de Man), a species which is found in the Persian 

 Gulf, is probably identical, while Scyll. bicuspidatus is most closely related to Scyll. arctus (L.). 

 Scyll. orientalis (Sp. Bate) ranges from the Philippine Islands to the Arabian Sea, occurs also 

 in the Bay of Bengal and has been dredged by this expedition between Rotti and Timor and 

 off Sumbawa. Scyll. riibens (Alcock and Anderson) is still only known from the Gulf of Manar, 

 off Colombo; two species, hnally, are recorded from the Red Sea: Scyll. putnilus Nob. and 

 Scyll Paulsoni Nob. 



Seven species have until at present been observed in the Indian Archipelago, but two 

 other ones, Scyll. tuberculatus (Sp. Bate) and Scyll. cultrifer (Ortm.) will, no doubt, once prove 

 to occur also in it. 



The species of this genus are generally found in shallow water and some are even 

 inhabitants of the coralreefs, like Scyll. sordidus, Scyll. vitiensis and Scyll. tuberculatus. The 

 typical Scyll. arctus occurs in the Adriatic and the Mediterranean in water of 2 — 10 fathoms, 

 but the same species was taken at 49 fathoms off Cape Hatteras, N. C, and it was dredged 



in 25 80 fathoms off the Amirante bank; the variety paradoxus Miers was found in Goree 



Bay between 9 and 1 5 fathoms. Scyll. pygmaeus and Scyll. depressus were taken at depths 

 respectively of 78 and 86 fathoms, while Scyll. amcricanus was collected on the reef and in 

 shallow water between 2 and 45 fathoms. Scyll. Martensii was dredged off the Hawaiian Islands 

 between 230 and 53 fathoms, but it was captured by this expedition in water of 14 — 36 meters. 

 Scyll. orientalis was obtained off the Madras coast at 91 fathoms and in the Indian Archipelago 

 at depths of 216 and 274 meters, Scyll. cultrifer (Ortm.) in the Arafura Sea at 140 fathoms 

 and in Japan at a depth of 145 meters, while Scyll. rubens was dredged in the Gulf of Manar 

 between 142 and 400, as also between 180 and 217 fathoms. The other species, finally, are 

 found at a depth of less than 75 fathoms, while about the vertical distribution of Scyll . pu/uilus, 

 Scyll. Paulsoni and Scyll. Nobilii nothing is known. 



Key to the indopacific species of the genus Scyllarus Fabr. 



a 1 Thoracic legs of 3" 1 pair subcheliform. Abdominal terga with distinct 

 squamiform sculpture. Proximal (outer) antennal squame with two 



teeth both on the outer and the inner margin cultrifer (Ortm.) 



(A. E. Ortmann, in: Zoolog. Jahrb., Abth. f. Syst. T. X, 1897, p. 272). 

 «., Thoracic legs of 3" 1 pair not subcheliform. 



b Y Second and following abdominal terga deeply sulcate transversely, 

 devoid of arborescent markings, at least on the i st and the 



2 nd. ord som ite with a large prominent gibbosity tuberculatus (Sp. Bate) 



(C. Spence Bate, Report Challenger Macrura, 1888, p. 70, PI. X, fig. 1 and 2). 

 6., Abdominal terga not deeply sulcate transversely. 



c x Abdominal terga without any distinct arborescent markings, 



