BALL: MOLLUSCA AND BUACIIIOPODA. 433 



of the rostrum corresponding to tlie dorsal area smooth. Lon. of shell, 27 ; of 

 posterior end, 16; alt. 17; diam. 15 mm. 



U. S. S. "Albatross," station 3392, in the Gulf of Panama, in 1270 fathoms, 

 hard bottom, temperature 36°. 4 F. 



It is possible that more material may show that this is merely a variety of 

 C. planetira, but for the present it seems safer to keep tliem separate. As in all 

 these species, the basal margins are somewhat flexuous. Measurements have 

 been made for the length of the shell parallel to the hinge line, and the height of 

 the shell is taken at right angles to this length. 



Cuspidaria (Cardiomya) planetica Dall, n. sp. 



This species has a generally similar aspect to the C. pseuates above described 

 and differs in the following particulars : the rostrum is less constricted at tlie 

 proximal end, so that the whole shell is more attenuated backward ; there is not 

 so much distinction between tlie disk and tlie rostrum ; the impressed area, along 

 the dorsal margin, is smaller and is not amphidetic, but ceases to be defined in 

 front of the beaks; the radial major threads appear stronger and less numerous ; 

 the chondrophore or fossctte is much less conspicuous and is formed by a small 

 pit in the cavity under and almost behind the hinge margin, while in pseustes it 

 is a comparatively large vertically projecting spoon-shaped process*; the general 

 form of C. planetica is more elongate and the anterior patulous extension is directed 

 forward rather than obliquely downward ; lastly C. planetica is uniformly smaller. 

 Leugth of shell, 24; of posterior part behind the beaks, 13; alt. 14; diam. 

 11 mm. 



U. S. S. "Albatross," station 2925, off San Diogo, California, in 339 fathoms, 

 mud, bottom temperature 42°.9 F. Types U. S. N. Mus. 110,720. Also at 

 station 3400, east of the Galapagos Islands, in 1322 fathoms, ooze, temperature 

 36° ; station 3059, off Siletz Bay, Oregou, in 77 fathoms, m\id, temperature 45°.l ; 

 and station 3609, in Bering Sea, southeast of the Pribiloff Islands, in 74 fathoms, 

 mud and sand, bottom temperature 38° F. It has also been collected from deep 

 water, 85 fathoms, in Captain's Harbor, Uualashka, Aleutian Islands. The ex- 

 treme stations are about 3500 miles apart. 



A few specimen stations have been selected to show the immense range of this 

 widely distributed species. It will be noted that it descends from about 80 

 fathoms in the north to over 1300 fathoms in the tropics, following the sea 

 isotherms, and this I may add without altering its appearance in the least, 

 notwiliistanding the immense difference in pressure. Living in these depths 

 near tlie Galapagos Islands, it would be uo surprise to find it anywhere still 

 farther south. 



Cuspidaria (Luzonia) chilensis Dai.l. 



Cuspidaria (Luzonia) chilensis Dall, Troc. U. S. Nat. Mus., 1880. 12. p. 282, pi. 13. 

 fig. 13. 

 vol,. XI.IH. — NO. 28 



