NO. 2283. ]fEW PACIFIC COAST CHITONS— DALL. 513 



with six slightly elevated ribs, the anterior pair bifurcate, internally 

 with seven slits, the sinus shallow and rounded, the sutural laminae 

 rather wide and not rounded ; intermediate valves slightly mucronate. 

 the jugal area axially striate and rounded, the pleural tracts axially 

 threaded with transverse minuter threads in the interspaces, the 

 lateral areas very narrow with two strong nodulous ribs (sometimes 

 bifurcate) and the posterior margin minutely denticulate: Length, 

 10; width, 4.5; height, 2.2 mm. 



Hahifaf. — Duncan Island, Galapagos Islands, United States Fish 

 Commission steamer Albatross. Cat. No. 218772 U.S.N.M. 



MOPALIA CHLORIS, new species. 



Chiton low, wide, of moderate size, of a dark bronze green, with 

 leathery girdle which when fresh had a few slender, sparsely dis- 

 tributed hairs upon it (lost in the dry specimen) ; anterior valve with 

 eight slits, externally with about ten radiating conspicuous threads 

 with a few feebler shorter intercalary' threads, over the whole of 

 which is a faint very minute oblique decussation; posterior valve 

 small, with a very low subcentral mucro and a faint concave 

 wave medially behind, over which is a white ray ; it has two slits and 

 a narrow rounded jugal sinus with wide sutural laminae, the finer 

 sculpture is like that of the anterior valve with one or two radial 

 threads; intermediate valves with one slit, the jugal tract acute, with 

 the pleural tract sculptured with oval punctures between oblique 

 almost obsolete minute threads ; the lateral areas defined by a single 

 cord, otherwise similarly sculptured; interior bluish-white, the jugal 

 sinus narrow, rounded, the sutural laminae broad, the insertion i^lates 

 smooth; gill rows ambient. Length, 19; width, 11; height, 3 mm. 



Habitat.— San Diego, California ; Mrs. N. Davie. Cat. No. 293686 

 U.S.N.M. 



This at first sight recalls M. Mndsii or Ugnosa but the sculpture is 

 quite different. 



MOPALIA GONIURA, new species. 



Chiton of small size with a high arched back, of a jT^ellowish color 

 flecked with scarlet; the girdle red, velvety, with numerous sparsely 

 scattered large brown spines (broken off in the type) chiefly near the 

 inner border, and smaller ones scattered near the outer part; gill 

 rows about two-thirds the length of the foot; anterior valve with 8 

 slits, posterior with 4, intermediate valves with single slits ; anterior 

 valve with 10 radii, the two marginal wider, otherwise the surface 

 is covered with punctate reticulation; posterior valve small, the 

 mucro at the posterior third, sculpture of the posterior tract in 

 radial lines of pustules, the central area has very similar orna- 

 mentation ; the posterior sinus is narrow A-shaped, the apex reaching 



G2055— 20— Proc.N.M. Vol.55 34 



