296 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



Description: Posterior half of dorsum flattened, enclosed by a ridge 

 which posteriorly becomes a broad concave lamella projecting over the 

 posterior margin ; four equidistant spines on this margin, two median, 

 the gastric spine at the highest point of the carapace, the other two bran- 

 chial, above the widest part of the carapace. Cardiac region a rounded 

 nodule. Two small protogastric spines. Rostrum bifurcate for half its 

 length, horns tapering, acute, widely divergent. A short but well marked 

 supraocular spine. Basal antennal article much widened, especially poste- 

 riorly, there forming a strong lobe on the margin ; tooth at anteroexternal 

 angle a little more advanced than that at anterointernal angle. A small 

 lobe behind outer margin of basal article and in transverse line with 

 antennal glands. Anterointernal outline of merus of external maxilliped 

 oblique, slightly notched. 



Chelipeds of largest male examined, which may not have reached its 

 full development, just as long as next leg, palm slightly narrowed dis- 

 tally, gape of fingers slight. 



Abdomen of male widened a little at end of sixth segment. (Rath- 

 bun, 1925) 



Male abdominal appendages of the first pair somewhat flattened, 

 reaching to the last segment of the abdomen, and tapering very little 

 toward the extremity; extremity truncate and expanded, with a fold on 

 the outer and a small slender hook on the inner side. (Stimpson, 1871a, 

 P. 96) 



Although considerable variation is present among the extensive series 

 of Notolopas lamellatus examined, lots from given localities show such 

 remarkable uniformity with respect to certain important characters as to 

 suggest that the variation has a geographical basis. Gulf of California 

 specimens, especially those from the north, are large (19.3 mm?) as 

 compared with those from Ecuador (13.0 mm $). They show a long 

 rostrum with widely divergent horns, a strong preorbital but no inter- 

 mediate orbital spine, a postocular cup basally broadened, and strong 

 protogastric spines. The same type, but more generally without the pre- 

 orbital spine, occurs as far south as Costa Rica commonly, and sporadi- 

 cally to Ecuador, where individuals are of larger size than the prevailing 

 local form. The Ecuadorean specimens, as exemplified by a splendid series 

 from La Libertad, station 209-34, have a well developed intermediate 

 spine between the preorbital spine and the postocular cup. The carapace 

 is widest basally, instead of medially, and if supernumerary spines are 

 present, they tend to be the intestinal and (rarely; an ovigerous female 

 from station 9-33) the cardiac. This form occurs occasionally as far 

 north as Guatemala. 



