Cumacea: 22. Gynodiastylidae, 1. (Tynodiastylis, 23. Heteroleuconidae 163 



3. G. eostatus Calm. 1911 G. costata, Caiman in: Tr. zool. Soc. London, 

 rl8iv p. 342, 368, 372 t. 36 f. 1—10 j 1912 G. eostatus, T. Stebbing in: Ann. S. Afr. Mus., 

 V. lOv p. 147. 



Pseudorostral lobes and carapace much as iu G. carlnatus, but the 

 ridges more numerous, some ill defined and inteiTupted, and just behind the 

 sharp antero-lateral corners a short vertical pair, forming a tubercle behind 

 the sinus, are continued upwards, caiTying a series of thin, transparent, curved 

 spines. Pedigerous segments of the Q much as in G. carlnatus, but only the 

 third with a pair of slightly marked dorso-lateral ridges. Pleon segment 

 6 little shorter than 5**^; telson about ^4*^^ of 6*^, with 2 extremely minute 

 setae or spinules at the bluntly pointed apex. Eye without pigment. An- 

 tenna 1,.2'^<^ joint only half as long as 3*^. Antenna 2 in Q short, 4-jointed: 

 in the 6 also very short. Peraeopod J, 2"*^ joint scarcely half rest of limb, 

 5*^ joint twice the 6'^ which has about 11 long setae on the oblique distal 

 part, 7*^ joint more than half the 6*^. Exopod on all the first 4 pairs of 

 peraeopods in the 6, on only the first 2 in the 9. Peduncle of uropods 

 longer than 6**^ pleon segment, exopod in 9 nearly as long as peduncle, a 

 little shorter than the endopod, of which the P* joint is slightly shorter 

 than the 2"<^, but in d the peduncle is twice as long as the subequal rami. 

 L. 9 2*35 mm, d 1*9 mm. 



Gulf of Siam, Koh Kam, 37 m; N. of Koh Chuen, 27 m; between Koh Mesan 

 and Cape Liont, depth 9 — 15 m. 



4. G. bicristatus Calm. 1911 G. bicristata, Caiman in: Tr. zool. Soc. London, 

 c. I81V p. 842, 368, 374 t. 36 f. 11—22 | 1912 G. bicristatus, T. Stebbing in: Ann. S. Afr. 

 Mus., ?;. lOv p. 147. 



Pseudorostral lobes short, truncate, in 9 horizontal, a little depressed 

 in d, sinus well defined. Carapace with pair of strong cristiform ridges, 

 diverging from hind margin forwards and then converging on to the sides 

 of the pseudorostral lobes; eyelobe broad. Pedigerous segments each with 

 pair of dorso-lateral crests, indistinct on the b^^: side-plates of 3*^ not greatly 

 expanded, with no great interval between 2"*^ and 3*^ peraeopods. Pleon segment 

 5 little longer than the 4*^. Telson a little shorter than the preceding segment. 

 Eye without pigment. Antenna 1, 2^^ joint more than half the 3*^. An- 

 tenna 2 of 9 3-jointed, of 6 very short. Maxilliped 1 apparently without 

 branchial leaflets. Peraeopod 1, 2^^ joint about half rest of limb, 5*^ more 

 than twice 6*^. which has distally about 9 very long setae, 7*"^ little over 

 half the G*'^. Exopods on all the first 4 pairs of peraeopods in the d, only 

 on first 2 in Q . Peduncle of . uropods about twice as long as the telson, 

 exopod shorter than endopod, which is considerably shorter than the peduncle, 

 with 1^* joint shorter than 2'^'^. L. 9 1-9 mm, d 1*7 mm. 



Japan, 73 m; Gulf of Siam Koh Kam, 9 — 18 m; between Koh Mesan and Cape 

 Liont, depth 9 — 15 m. 



23. Fam. Heteroleuconidae 



1912 Heteroleuconidae, T. Stebbing in: Ann. S. Afr. Mus., ».10v p. 133, 156. 



Telson wanting. Second antenna in female three-jointed, the flagellum 

 in male very short. Mandible with base broad, molar obtuse. First maxilla 

 Avith single filament to the palp. Only the first two pairs of peraeopods 

 with exopods in either sex. No pleopods in male or female. Uropods with 

 endopod simple. 



1 genus. 



