FISHERY BULLETIN: VOL. 83, NO. 1 



Figure 41. — Sicyonta aliaffinis ,6 16 mm cl, west of Puerto Madero, Golfo de Tehuantepec, Mexico. A , Petasma, dorsal view; 

 B, ventral view of same; C, right appendix masculina, dorsolateral view. Scale = 1 mm. 



about 27 mm tl, but may not be joined in individu- 

 als as much as 11 mm cl, about 36 mm tl. 



Appendix masculina as illustrated in Figure 

 41C. 



Thelycum (Fig. 42) with plate of sternite XIV, 

 delimited anterolaterally by strongly convex mar- 

 gins, flat or very slightly raised in paired ill- 

 defined bulges flanking depressed median portion. 

 Median plate of sternite XIII flask-shaped in out- 

 line, tapering gradually into long, slender spine 

 reaching as far as distal margin of coxae of an- 

 teriorly extended second pereopods; posterior 

 component of plate with posterolateral margins 

 strongly arched and separated by median emargi- 

 nation variable in width. Sternite XI armed pos- 

 teriorly with paired short spine. Posterior thoracic 

 ridge with weakly concave or virtually straight 

 anteromedian portion slightly elevated, but areas 

 lateral to it merging indistinctly with plate of 

 sternite XIV. 



The smallest impregnated female encountered 

 has a carapace of 5 mm, about 23 mm tl. 



Color. — Specimens from Peruvian waters were 

 described by Arana Espina and Mendez G. (1978) 

 as follows: dorsum dark, petroleum green; 

 carapace lighter laterally, exhibiting various 

 shades of gray, green, or pink, and bearing striking 

 dark mark resembling longitudinally disposed "9" 

 on branchial region. Antennae with light and dark 





Figure 42. — Sicyonia aliaffinis, * 25 mm cl, west of Puerto 

 Madero, Golfo de Tehuantepec, Mexico. Thelycum. Scale = 2 



50 



