HAYNES: LARVAL MORPHOLOGY OV PA.\DAU'S TRIDE.WS 



pleurobranchiae. Spines on posterior margins of 

 abdominal somites similar in size and number to 

 spines in Stage I. 



ANTENNULE i Figure 2B).— Three-segmented; 

 bears large lateral flagellum and smaller inner 

 flagellum on terminal margin. Inner flagellum 

 unsegmented, conical, and has one long spine ter- 

 minally. Outer flagellum has five aesthetascs of 

 various lengths and one plumose .seta. Proximal 

 segment bears four setae laterally near base, 

 single seta subdistally. and two setae distally. 

 Second segment has two setae distally. Distal 

 segment has four plumose setae laterally near 

 inner flagellum and has small seta laterally and 

 subdistally. 



ANTENNA i Figure 2C i.— Flagellum styliform, 

 about one-third length of scale. Antennal scale 

 about 5'2 times as long as wide and fringed along 

 distal and inner margins with 22 long, thin 

 plumose setae. Antennal scale still divided dis- 

 tally into four joints; bears two setae on lateral 

 margin: one at base of proximal joint, one proxi- 

 mally. Protopodite bears spine at base of flagellum 

 but no spine at base of scale. 



MANDIBLES (Figure 2D).— Incisor proce.sses of 

 both mandibles more pronounced and have more 

 teeth than in Stage I. Molar processes somewhat 

 more developed than in Stage I, especially forw-ard 

 lip of truncated end. 



MAXILLULE. — Similar in shape to maxillule of 

 Stage I, except coxopodite and basipodite each 

 bear additional spine. 



MAXILLA. — Shape similar to Stage I maxilla, ex- 

 cept scaphognathite is slightly longer proximally, 

 bears 9-11 marginal plumose setae, and large 

 plumose seta at proximal end. Endopodite same as 

 endopodite of Stage I. Lobes of basipodite bear 

 either 6 + 6 or 7 -i- 5 setae; lobes of coxopodite bear 

 3 + 11 or 3 + 12 setae. 



THIRD MAXILLIPED.— Dactylopodite (Figure 

 2Fi narrower, longer than in Stage I. 



FIRST AND SECOND PEREOPODS (second 

 pereopod shown in Figure 2Gi. — Endopodites of 

 first and second pereopods functionally developed, 

 five-segmented and terminating in simple conical 

 dactylopodite. Exopodite of first pereopod is 

 longest exopodite of pereopods. Exopodites of first 

 and second pereopods have two terminal and eight 

 lateral natatory setae. 



THIRD PEREOPOD ( Figure 2H ).— Exopodite and 

 endopodite nonfunctional but segmented at base. 

 Endopodite tipped by four simple setae. 



FOURTH AND FIFTH PEREOPODS (Figure 

 21 1. — Poorly developed, unsegmented. and with- 

 out exopodites. 



TELSON (Figure 2Ji.— Telson similar in shape to 

 Stage I, but distinctly segmented from sixth ab- 

 dominal somite. Telson has eight pairs of densely 

 plumose setae. Uropods still enclosed. Anal spine 

 present but minute. 



STAGE III ZOEA 



Total length of Stage III zoea 5.9 mm (range 

 .5.6-6.3 mm; 7 specimens!. No change in shape of 

 rostrum from Stage II. Spines along anteroventral 

 and posteroventral margin of carapace still pres- 

 ent, but minute and fewer than in Stage II. Epipo- 

 dite on first maxilliped still only gill structure 

 present. Spines on posterior margins of abdominal 

 somites smaller than in Stage II. 



ANTENNULE.— Similar in shape to antennule of 

 Stage II but bears several additional setae; a 

 spine projects downward from ventral surface of 

 proximal segment. From this stage on, change in 

 antennule slight: inner flagellum lengthens, more 

 setae on antennule. 



FIRST MAXILLIPED (Figure 2Ei.— Epipodite of 

 first maxilliped longer than in Stage I. Setation 

 formula of endopodite 3, 2, 1, 3. Protopodite un- 

 segmented, bears about 20 setae. 



SECOND MAXILLIPED.— Same as Stage I, ex- 

 cept each segment of endopodite may have an ad- 

 ditional seta. 



ANTENNA.— Flagellum styliform, two- 

 segmented, still only about one-third length of 

 scale. Antennal scale about six times as long as 

 wide; two complete joints at tip (Figure 3A). Ter- 

 minal spine on lateral margin of scale does not 

 quite reach tip of scale. Protopodite bears small 

 spine at base of flagellum and minute projection at 

 base of scale. 



629 



