168 Cumacea: 24. Nannastacidae, 2. Paranannastacus, 3. Nannastacus 



iiropods about half, exopod less than a fifth, as long as the endopod: termiual 

 spine of exopod much longer than that of endopod. L. 9 TS mm. d unknown. 



Gulf of Siam, depth 2 m. 



2. P. tardus (Calm.) 1911 Nannastacus t., Caiman in: Tr. zool. Soc. London, 

 ti. I81V p. 341. 359 t. 34 f. 4 — 11 \^\2 ParanannastacxiS t., T. Stebbingin: Ann. S. Afr. Mus.,' 

 %\ lOv p. 164. 



Pseudorostral lobes shortly produced, slightly upturned, truncate, meeting 

 in the middle line below, and apparently also above, the branchial orifice, 

 antero-lateral margin deeply concave, antero-lateral corner strongly produced, 

 serrate below. Carapace considerably broader than deep, with branchial regions 

 little inflated. Pedigerous segment 1 reduced to laterally expanded side- 

 plates with marginal laminar spines; the next segment with small median 

 dorsal tooth. Pleon segment 1 with pair of small dorso-lateral teeth, often 

 (perhaps accidentally) absent. The pair of eyes as figured rather smalL 

 Antenna 1, 2""^ and 3"^ joints subequal, and combined in length subequal to 

 the stouter P* joint. Maxilliped 3 and peraeopods 1, 2, without exopods, 

 with 2>^*^ joint not elongate, but in the maxillipeds having a long nan'ow distal 

 process, and in peraeopod 1 having a prominent rounded lobe on the medial 

 margin. Uropods differing from those of P. reptans (p. 167) chiefly by the 

 terminal spine of the exopod, which is shorter instead of much longer than that 

 of the endopod. L. Q 1"6 mm. d not known. 



Gulf of Siam; depths between 9 and 28 m. 



3. Gen. Nannastacus Bate 



1865 Nannastacus (Sp. typ.: Cuma unguiculata), Bate in: Ann. nat. Hist., ser. 3 

 V.15 p. 86 I 1878 & 1879 N., G. O. Sars in: Arch. Naturv. Kristian.. v.S p. 566: vA p. 108 [ 

 1880 N, Kossmann, Reise Eoth. Meer., Malac. pars 2 p. 90 | 1887 N., G. 0. Sars in: 

 Rep. Voy. Challenger, v. 19 pars 55 p. 62 | 1893 N., T. Stebbing in: Int. sci. Ser., 

 r. 74 p. 305 | 1900 N., G. 0. Sars, Crust. Norway, v. 3 p. 79 | 1900 N., T. Stebbing in: 

 Willey, Zool. Results, pars 5 p. 611 j 1904 iV^., Caiman in: Herdman, Rep. Ceylon Pearl 

 Fish., V.2 p. 176 | 1905 N, Caiman in: Sci. Invest. Pish. Ireland, 1904 app. 1 p. 23 | 

 1905 N., Caiman in: Siboga-Exp., nr. 36 p. 10 | 1911 N^., Caiman in: Tr. zool. Soc. London, 

 V. I81V p. 350 I 1912 iV., T. Stebbing in: Ann. S. Afr. Mus., v. 10 v p. 164. 



Antero-lateral angles of carapace well defined. Eyes, when present, 

 divided into a distinct pair. Maxilla 1 with 2 filaments to the palp. Third 

 maxilliped with exopod in the male, but not always in the female. First 

 two peraeopods with exopods in the female. Uropods with endopod longer, 

 generally much longer, than the exopod. 



16 species. 

 Synopsis of species : 



I Third maxilliped without exopod in the female — 2. 



\ Third maxilliped with exopod in both sexes — 6. 



( Antero-lateral angle of carapace obtuse — 3. 



] Antero-lateral angle of carapace acute — 4. 



) Antero-lateral angle of carapace armed with a spine . 1. N. zimmeri 



\ Antero-lateral angle of carapace without spine .... 2. N. sulunii 



Uropods with endopod nearly thrice as long as peduncle 3. N. gibbosus 



Uropods with endopod not nearly thrice as long as 

 peduncle — 5. 



{Carapace little broader than deep 4. N". minor 

 Carapace considerably broader than deep 5. N. agnatus 



