segments of swimming legs with rows of spines (see 

 below). Caudal rami and caudal setae symmetrical. 



Female. — Prosome in dorsal view slender to robust 

 ovoid, head rounded or with prominent crest. Ros- 

 trum 2 sharp, vertically directed, spines; sometimes 

 asymmetrical. Th5 lateral corners prolonged; 

 Thl-Th4 without lateral spinules. Prosome length 3- 

 3' 2 times urosome. Genital segment sometimes 

 asymmetrical; protruding ventrally one-half depth of 

 rest of urosome. Caudal rami length l'/2-2 times 

 width. 



Al segment 2 length at least l'/2 times segment 1; 

 segments 8 and 9 fused. 



A2 Re length exceeding Ri by about 20%. Published 

 information on A2 segmentation contradictory; 

 probably Re2 with 2 setae and at least partly fused 

 with Re3. 



Mn B2 with 4 inner setae. 



Mxl gnathobase as in Spinocalanus; distal anterior 

 seta apparently absent. Inner lobe-1 with 5 setae. 

 Outer lobe-2 small, with 1 short seta. 



Mx2 length 1 '2 times width; proximal outer hump 

 nude. Lobe-5 with 4 strong setae; posterior surface of 

 base without spines. Lobe-6 small, with 2 setae. Ri 

 segments not reduced. Mx2 outer seta apparently ab- 

 sent. 



Mxp Bl with or, apparently, without transverse 

 spine-comb midlength on outer anterior and posterior 

 edge. B2 without spine-comb. Bl with proximal and 

 midlength group of 3 setae each; distal group ap- 

 parently with 4-6 setae. B2 with longitudinal row of 

 stiff hairs; 2 setae about midlength, 1 seta more distal, 

 and 2 distal setae. Ri4-5 outer setae relatively short 

 and thin, probably lightly plumose; Ri5 inner edge 

 without spinules. 



PI Re3 apparently without posterior surface spines. 



P2-P3 Re2 posterior surface probably with row of 

 small spines; P4 Re2 with 2 rows of spines. 



P2-P3 Re3 posterior surface probably with 2 distal 

 rows of spines. P4 ReS posterior surface with 

 longitudinal series of small spines. 



P2-P4 Re terminal seta with finely serrate outer 

 edge; outer flange narrow. 



P2-P4 Ri2 posterior surface with 2 rows of spines. 

 P3-P4 Ri3 posterior surface with 2 rows of spines. 



P4 Bl with transverse row of long spinules on inner 

 posterior surface; length variable, sometimes 

 asymmetrical or lacking on right. 



Male. — Adult known only for M. typica. See also 

 Monacilla sp. (= M. typica.— Wheeler, 1970). 



Key to the Species of Monacilla 



1. Female: Prosome slender ovoid, anterior crest. 



(Male unknown.) 2. M. tenera 



Female: Prosome robust ovoid, no anterior crest 

 (2) 



2. Female: Genital segment symmetrical, not pro- 

 truding on right; P4 Bl inner posterior surface 

 with transverse row of spinules, equal length 



left and right. (Male unknown.) 



7. M. gracilis 



Female: Genital segment asymmetrical, pro- 

 truding on right; P4 Bl inner posterior surface 

 with transverse row of spinules, longer on left, 

 sometimes absent on right. Male: Length 

 1.59-2.3 mm. PI Rel outer spine reduced to mi- 

 nute seta; PI Re2 outer spine forming sharply 



curved hook; P5 left Ri styliform 



1. M. typica 



1. Monacilla typica Sars, 1905 



Monacilla typica Sars, 1905, p. 9. —Sars, 1924, 1925, 

 p. 38-40, pi. 11, fig. 1-15; pi. 12, fig. 1-10. —Rose, 

 1933, p. 87-88, fig. 49. — Vervoort, 1946, p. 158-163. 

 —Wilson, 1950, p. 267, pi. 26, fig. 380. — Farran 

 and Vervoort, 1951b, p. 2-3, fig. 3b-e, h-i. — Tanaka, 

 1956, p. 396-397, fig. 18. — Owre and Foyo, 1967, p. 

 42, fig. 88, 92, 226-227, 229-230. — Grice, 1971, p. 

 276-279, fig. 2J-K, 3A-B. 



Oxycalanus spinifer Farran, 1908, p. 25-27, pi. 1, fig. 

 11-17. 



Oxycalanus semispinus Scott, 1909, p. 33-34, pi. 2, 

 fig. 9-21. 



Monacilla dubia Scott, 1909, p. 35-36, pi. 3, fig. 17-29. 



Monacilla semispina. — Wilson, 1950, p. 266-267, pi. 

 26, fig. 379. 



Monacilla typica var. asymmetrica Tanaka, 1956, p. 

 398, fig. i9. 



Type Specimens: Syntypes, females (2.30 mm), Musee 



Oceanographique de Monaco (Belloc, 1960); on slides 



F5052-F5058, OSLO. 



Type Locality: East and northeast Atlantic, 1,000- 



1,200 m. 



Material Studied: l male (1.75 mm), sample 39 



(Table 3); 1 male (1.72 mm), sample 40. 



Description 



Female. — Length 1.95-2.5 mm. Prosome in dorsal 

 view robust ovoid; head rounded, without crest. In 

 lateral view with fairly abrupt forward slope. Rostrum 

 2 sharp, vertically directed spines, symmetrical. 

 Prosome length 3' 2 times urosome. Genital segment 

 asymmetrical, somewhat protruding on right. Caudal 

 rami length 1 ' 2 times width. 



Al reaching anal segment. 



Mxp Bl with transverse spine-comb midlength on 

 outer edge. B2 with cluster of spinules about one-third 

 length on outer edge. 



P4 Bl transverse row of long spinules on inner 

 posterior surface more developed on left, sometimes 

 lacking on right. 



[Sars ( 1905, 1925) reported P5 as reduced to simple 



64 



