188 THE PTEROPODA 



As Pelseueer (1888, p. 35) pointed out, the empty shells 

 do not exhibit the reticulated sculpture as is seen in the 

 shell of the living animal. I noticed that this reticulation 

 is nearly quadrangular on the penultimate whorl and that 

 an umbilicus scarcely exists. The only living specimen proved 

 to be a young one by the extension of the reticulation on 

 the last whorl, by its small size (2 mm.) and by the number 

 of the whorls (S'/^)- It belongs to the type, as the variety 

 minor ^ established by me (p. 15, PL I, fig. 4), has at a 

 size of 1,25 mm. already 4 whorls. 



The empty shells, purchased from Mr. Preston under 

 the name of Peraclis diversa Monterosato, really belong, 

 in my opinion, to P. reticulata. We owe to A. Locard 

 (p. 29, PI. I, figs. 4 — 6) an accurate description, accom- 

 panied by figures, of the species of de Monterosato. 

 From this description it appears that P. diversa is distin- 

 guished : 1° by the obliquely rolling up of its whorls, 2° 

 by the suture, ornated with radiating, equidistant crests, 

 3° by the narrow and deep umbilicus. Now, the shells of 

 Preston entirely agree with P. reticulata^ the suture only 

 exhibiting the above-mentioned crests; but as Meisen- 

 heimer (p. 12) remarked, P. reticulata shows exactly the 

 same radiating crests. I failed to discover this feature in 

 the shell from the Indian Ocean ; nevertheless, as it may 

 be a character dependent on age (Meisenheimer's specimens 

 attained a height of 6 mm.), I feel justified myself in 

 designating the specimens of Preston under the name of 

 P. reticulata i 



Family II. Cavoliniidab. 



Genus 1. Creseis Rang. 



Species 1. Creseis virgula Rang. 



Animals: 



Mediterranean, date? some sp., Buitendijk. 



// May '05, // // 



// Decemb. '05, // // 



Notes from the Leyden Museum, Vol. XXIX. 



