PART 1 GARTH : PACIFIC OXYRHYNCHA 413 



Macrocoeloma maccullochae Garth 

 Plate Y, Fig. 4; Plate 46, Fig. 1 

 Macrocoeloma maccullochae Garth, 1940, p. 65, pi. 16, figs. 1-4. 



Type: Male holotype, A.H.F. No. 372, length 31.3 mm, width 

 including spines 20 mm, without spines 17 mm. (See also revised meas- 

 urements below.) 



Type locality: Isabel Island, Mexico, 10-18 fathoms, Velero III 

 station 747-37. 



Additional localities reported: Costa Rica: Playa Blanca [error for 

 Port Parker], Velero III (Garth). Ecuador: La Libertad, Velero III 

 (Garth). 



Atlantic analogue: Macrocoeloma trispinosum (Latreille). 



Diagnosis: Posterolateral spines acute, directed backward and up- 

 ward. Rostral horns subparallel, separated at bases by a narrow inter- 

 space. Basal antennal spine pointing obliquely outward. Carapace with 

 four dorsal bosses or tubercles arranged in a diamond. Male first pleopod 

 little constricted below apex, keel erect, slender; tip elongate, semicylin- 

 drical, channeled, recurving. 



Description: Carapace distended, subpyriform, broadened anteriorly 

 at the orbital level, and covered with a dense, woolly pile interspersed 

 with longer, yellow, hooked hairs. Gastric, cardiac, and branchial regions 

 swollen, each surmounted by a large boss or tubercle, the four forming 

 a perfect diamond. Carapace constricted at the hepatic level; two small 

 epigastric tubercles. Two strong, cylindrical, acuminate postlateral spines, 

 directed obliquely outward, backward, and upward. A smaller spine on 

 the posterior border at the mid-point, in front of it a boss or tubercle at 

 the intestinal level. A total of eight major prominences; with the two 

 epigastric, ten. Rostral spines long, cylindrical, tapering, not flattened, 

 contiguous from bases almost to tips; tips sharply divergent, except in 

 young specimens ; length of rostrum about four-fifths times the distance 

 between the preorbital spines. Orbits tubular, protruding beyond mar- 

 gins of carapace, postorbital spine extending beyond preorbital. Upper 

 orbital margin deeply incised, spines separated by a fissure fused distally 

 but open proximally and extending on to the hepatic region. 



Basal antennal article broad, bearing an obliquely directed spine. 

 Flagellum long, reaching four-fifths the length of the rostrum, its first 

 two movable segments appreciably thickened. A tubercle at the level of the 

 green-gland opening; a similar pterygostomian tubercle. Merus of third 

 maxilliped irregular in outline, anterointernal angle sharply produced, 



