PART 1 garth: pacific oxyrhyncha 417 



Macrocoeloma villosa, Miers, 1886, p. 79 (synonymy includes Pericera 



fossata Stimpson). 

 Macrocoeloma villosum, Rathbun, 1910, pp. 574, 616; 1925, p. 482, pi. 

 269, figs. 4-7, text-fig. 135. Crane, 1937, p. 63, pi. 3, fig. 12. 



Type: Male, originally deposited in the Museum of the Zoological 

 Society [London], and female, originally deposited in the Bell Museum, 

 cotypes; neither type is extant. Length of measured cotype 40.2 mm, 

 width including spines 40.2 mm. 



Type locality: Bay of Guayaquil, Ecuador, 11 fathoms; Hugh Cum- 

 ing, collector. 



Localities subsequently reported, with collectors: Lower California, 

 Mexico: L. Diguet (Bouvier) ; Cape San Lucas, John Xantus (Stimp- 

 son, as Pericera fossata). Gulf of California, Mexico: Santa Inez Point, 

 Zaca (Crane). Ecuador: Santa Elena Bay, E. Festa (Nobili). 



Atlantic analogue: Macrocoeloma subparallelum (Stimpson). 



Diagnosis: Posterolateral spines blunt, directed outward in young, 

 forward in adults. Rostral horns diverging from bases. Basal antennal 

 spine pointing forward. Carapace without dorsal spines but covered with 

 dense pile, posteriorly sculptured or areolated. Male first pleopod stout, 

 slightly constricted at base of bluntly trianglar keel, tip channeled, mod- 

 erately elongate, little recurving. 



Description : Surface everywhere covered with a uniform short, dense, 

 closely-adhering pubescence. A few curled setae on the rostrum, and on 

 the concave anterolateral slopes of the carapace. Lateral processes long, 

 blunt, and a little curved forward. Regions of the carapace protuberant 

 and separated by very deep sinuous pits or channels, appearing somewhat 

 as if eaten out; but the protuberances themselves not vermiculated. 

 Rostrum as long as the distance between the eyes; horns diverging, 

 the distance between their tips equaling about two-thirds that between 

 the orbits. Spine of the basal [article] of the antennae slender, and reach- 

 ing considerably beyond the preorbital tooth. 



Abdomen in the female showing a deep, vermiculated furrow on each 

 side of the median rounded ridge, also channelled sutures. (Stimpson, 

 modified, of Pericera fossata) 



A 16.1 mm male from Agua Verde Bay, Gulf of California, resem- 

 bles the 9.6 mm male from near Santa Inez Point (Crane, 1937, pi. 3, 

 fig. 12) in having the postlateral spines directed slightly backward instead 

 of forward. Comparison with a 20.7 mm male from Salinas (U.S.N.M. 

 No. 70942), smallest in the Ecuadorean series, shows this to be the 

 normal condition in the young. The Agua Verde Bay specimen, how- 



