MUSEUM OF COMPARATIVE ZOOLOGY. 397 



out claiming it as his own, or differentiating it from other older genera quoted 

 by him, three years after its use by James Sowerby. 3. Other authors have 

 referred to Defrance as the author of the name, but without stating any grounds 

 for it, and without noticing Sowerby's original use of it. Hence it is evident 

 that there is no published proof that the name is due to any one but Sowerby. 

 What tradition may assert, or heedless quotation have established, is another 

 matter, with which I do not feel that I have authority to deal. 



Section PEROTROCHUS Fischer. 

 Pleurotomaria (Perotrochus) Quoyana Fischer & Bernardi. 



Plate XXIX. Fig. 1. Plate XXXI. Figs. 1, lb, 1 c. Plate XXXVII. Fig. 5. 



Pleurotomaria Quoi/ana Fischer & Bernardi, Journ. de Concliyl., V. p. 165, pi. v. 

 figs. 1-3, 1856. Dall, Bull. M. C. Z., IX. p. 78, 1881. Crosse, Journ. de 

 Conchy I., XXII. p. 14, 1882. Dall, in Agassiz, Three Cruises of the Blake, 

 II. p. 69, fig. 289, Jan., 1888. 



Habitat. Station 290, off Barbados, in 73 fms., coral sand, bottom temper- 

 ature 70°. 75. Station 296, off Barbados, in 84 fms., hard bottom, temperature 

 61°. 5 F. Island of Marie-Galante, near Guadelupe, Fischer. Station 2354, 

 off the coast of Yucatan, near Arrowsmith Bank (dead), in 130 fms., coral bot- 

 tom, U. S. Fish Commission. 



The first mentioned specimen was a little defective about the aperture, 

 though living. It is in the U. S. National Museum. The second, also living, 

 is perfect, and is now in the Museum of Comparative Zoology at Cambridge. 

 The Fish Commission specimen, also in the National Museum, is broken some- 

 what at the aperture, but otherwise in good order. All these shells were of 

 nearly uniform size. The measurements of the two Washington specimens 

 are as follows. Max. diam. at base, 50.0 and 48.0; min. diam., 47.0 and 43.0; 

 max. alt. of shell, 42.0 and 40.0; width of notch in both, 2.5 mm. Number 

 of whorls, 10 and 9^. Height of the, aperture, 15.0 and 13.5 mm. 



The early two or three whorls are tilled solidly with translucent yellowish 

 or reddish shelly matter, and the nucleus, as far as can be observed, shows no 

 trace of a notch. This form belongs to the section Perotrochus Fischer (1885), 

 but I do not think the value of most of these sections is very great. They are 

 merely convenient means of arranging large numbers of species which do not 

 greatly differ from one another. The characters of the radula may, however, 

 validate the present subdivision. 



The animal in alcohol is of a yellowish waxen color, varied on the back of 

 the tentacles, and on the upper part of the head behind the tentacles, with fine 

 black transverse lines, corresponding to the wrinkles between the cuticular 

 rugae. This led to the suspicion that they were due to foreign matter, but 

 both specimens presented essentially the same appearance. The whole surface 

 of the body was more or less rugose. The parts above alluded to are finely 



