COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 13 



Length 14 mm., height 14, diameter 4. 



The specimens from station 302 present one or two differences from 

 those found at the two other localities. The right [left] or deep valve 

 has some of the concentric lines of growth elevated into slender lirae, 

 which, crossing those radiating from the beak, produce a distinctly- 

 cancellated surface. Besides this, the valves are strengthened with twelve 

 instead of eleven radiating lirae. However, talcing into consideration the 

 exact similarity of the microscopic sculpture of the right [left] valve, 

 I believe it advisable to consider this form merely as a variety. 



Remarks: Jeffreys examined the Challenger specimens before Smith 

 published his report on them, and after his brief description of Amus- 

 sium lucidum striata referred those from Marion Island to his new sub- 

 species. Smith {loc. cit.) strongly disagreed, saying, "It is most sur- 

 prising to me that this species could for an instant be considered as a 

 variety of Amussium lucidum. Any one holding such a view must either 

 be wanting in perceptive power or his ideas respecting what are usually 

 regarded as species be very peculiar. If any two species of this genus are 

 to be easily distinguished, those in question are they. Amussium meri- 

 dionale is larger, gapes on both sides, has both valves differently sculp- 

 tured, a shorter hinge-line, and the posterior auricle in the left [right] 

 valve is differently sculptured." Dall (1886, p. 212) also disagreed with 

 Jeffreys, and in speaking of A. meridionale said, "It is at all events 

 perfectly distinct from lucidum. My impression is that Dr. Jeffreys 

 derived his idea of his variety striata from specimens of A. Pourtale- 

 sianujn, var. striatulum Dall [loc. cit.], sent him by Pourtales; but that 

 when he came to describe it he cited Challenger localities and specimens, 

 which on a cursory examination he took to be the same thing, and 

 omitted to mention his West Indian ones. However this may be, the var. 

 striatulum mentioned agrees perfectly with Dr. Jeffreys' rather brief 

 description of his variety striata, but not with his specimens." Dall's 

 omission of any reference to the "Porcupine" specimens is curious, but 

 whatever their taxonomic position may be, we can safely conclude that 

 they are distinct from Propeamussium meridionale. 



Geographical range: Known only from the type locality and from 

 Challenger stations 146, 40°46'S, 45°3rE (about 1250 miles south of 

 Madagascar), in 1375 fathoms, and 302, 42°43'S, 82°irW (about 600 

 miles west of south-central Chile), in 1450 fathoms. 



Bathy metric range: Recorded in 1375 to 1800 fathoms. 



Ecological data : Found in globigerina ooze at each station. 



