Cumacea: 11. Diastylidae, 1. Diastylis 103 



Norman & T. Scott. Crust. Devon Cornwall, [). 32 | 1909 1). r., A. M. Norman & G. S. 

 Brady in: Nat. Hist. Tr. Northnmb., ser. 2 v.'dn p. 32. 



Pseudorostral lobes couically produced, horizontal, antero-lateral corners 

 slightly marked in g , rounded and serrate in 6 ; carapace of g with 5 pairs 

 of transverse pleats, some rather indistinct and discontinuous, the frontal lobe 

 flanked l)y a conspicuous pair of forward pointing teeth and having to the 

 rear a smaller more approximate pair; carapace of (5 with 2 pairs of distinct 

 transverse pleats flanking the frontal lobe, the longitudinal lateral carinae 

 (juite smooth. Pedigerous segment 5 with front margin crenulate. postero- 

 lateral angles in 9 blunt, acutely produced in d. Pleon segments 1 — 6 smooth 

 in Q. in the d* P* with ventral crest of 3 spines. 1«* and 2°^ each with pair 

 of postero-dorsal denticles. 3*^ to 6*^ with postero-dorsal denticulate keel and a 

 pair of similar latero-ventral keels; telson considerably shorter than peduncle 

 of uropods, with 6 — 9 pairs of lateral spinules. Eye purple under white, 

 with 3 lenses, larger in d than in 9 . Antenna 1 9 long. 3'^ joint longer 

 than 1*^ 1^* longer than 2°*^, flagella well developed. Antenna 2 9, all the 

 joints small, flagellum in 6 very elongate. Peraeopod 1. 2°"^ joint shorter 

 than rest of limb. 6*^1 longer than S^h, more than twice as long as 7*^. 

 Peraeopod 2, 5*^ joint longer than 6^1^ and 1^^ combined. 1^^^ longer than <6^^. 

 3'^ and 4*'^ pairs without exopods in 9 . Exopod of uropods shorter than the 

 telson. more than half as long as the peduncle, endopod in 9 less than half 

 the peduncle, nearly half in 6. with 6. 3, 3 spines on medial margin of 

 the joints respectively in 9. 16. 8. 5. or more in d. 1^*^ joint in both 

 sexes subequal to 2"'^ and 3^^ combined. Colour grey-white. L. 9 8 mm, 

 6 9 mm. 



From Norway, Trondhjem Fjord, round to Messina in the Mediterranean, depths 

 surface to 73 m. 



25. D. tumidus (Lilj.) 1855 Cuma tumida, W. Liljeborg in: Ufv. Ak. Forh., 

 ^'. 12 p. 119 I 1859 Diastylis t., Danielssen in: Norske Selsk. Skr. 19. Aarh., v. 4 11 

 p. 108 I 1872 D. t., G. 0. Sars in: Forh. Selsk. Christian., 1871 p. 269 | 1883 D. tumidus, 

 <}. 0. Sars in: Forh. Selsk. Christian., 1882 nr. 18 p. 12 1 189-1 D. t, A. M. Norman in: 

 Ann. nat. Hist., ser. 6 a 13 p. 276 | 1900 D. tumida, G-. O. Sars, Crust. Norway, r. 3 p. 52 

 t. 40 I 1900 D. t., Zimmer in: Fauna arctica, v.l p. 425 (with synonymy). 434 | 1909 

 D.t., A. M. Norman & G. S. Brady in: Nat. Hist. Tr. Northumb., ser. 2 u3ii p. 32 | 

 1912 D. t, Caiman in: P. U. S. Mus., ^). 41 p. 605. 



Pseudorostral lobes not strongly produced, slightly upturned, antero- 

 lateral corners fairly marked, denticulate. Carapace tumid, in 9 nearly as 

 broad as long, smooth, in d with slight longitudinal keel low down on 

 each side: pedigerous segment 5 with postero-lateral corners obtuse in 9, 

 acutely produced in d: pleon segments 1 — 6 unarmed in 9. with scattered 

 denticles in d : telson shorter than the peduncle of the uropods. the distal 

 half armed with about 9 pairs of lateral spinules rather smaller than the 

 apical pair. Eye prominent, showing in d 5 lenses. Antenna 1 9. 1^* joint 

 shorter than 2°^ and 3^ combined. 3^ rather longer than 2'!'^. Antenna 2 d, 

 flagellimi very long. Peraeopod 1, 2"^ joint shorter than rest of limb. 5*^ shorter 

 than 6*''. 7^^ scarcely half as long as 6*^. Peraeopod 2, with 2 short teeth 

 on 3^ joint, S^^ as long as 6*'^ and 7^'^ combined, 7^^ considerably longer 

 than 6*^ 3^ and 4:^^ pairs in 9 without exopods. Peduncle of uropods 

 rather less than twice the exopod in Q, rather more in d; exopod rather 

 longer than endopod exclusive of the coalesced apical spine, spines on medial 



