MUSEUM OF COMPARATIVE ZOOLOGY. 245 



This species is not distinguishable from Chemnitz's figures, and his work is 

 only accidentally now and then binomial. Its name rests upon Orbigny's 

 figure and description. Doubtless he would have confounded it with T. mira- 

 bilis, but his figure identifies the species sufficiently. Adams may have con- 

 founded it with his own intermedins, and so named it, but his type specimens of 

 the latter are of a not rare variety of perversa. His description is eight years 

 later than the publication of Orbigny's Atlas, and his name would in any case 

 be out of court on that account, if they were identical. 



Section INELLA Bayle. 



Nucleus acute, conical, trochoid ; whorls flattened. 



The following schema of the species of this section may serve to assist the 

 student in identifying material which may come into his hands. In case of 

 any discrepancy between the figure and the diagnosis, the latter is always, in 

 this Report, to be regarded as the more correct. 



A. With three principal spirals. 



T. longissima Dall. Three spiral rows of very prominent tubercles; middle 

 tubercles opposite interspaces of the two outer rows; anterior row most promi- 

 nent of the three; a fine thread behind the suture; no transverse ribs. 



T. triserialis Dall. Three spiral tuberculated threads; tubercles axially 

 parallel; posterior row strongest; a fine thread behind suture; no ribs; shell 

 somewhat short and swollen. 



T. triserialis var. aspera Jeffreys. Last whorl but one of adult with 20 

 broadish, rather straight transverse ribs, overrun by two sharp not nodulated 

 threads with their posterior slope shortest; the ribs nodulous under the threads; 

 a nodulous smaller thread in front of the suture, a still smaller simple thread 

 behind the suture; whorls flat, shell elongate. The Antillean specimens have 

 more convex whorls. A specimen from the quaternary of Messina shows no 

 post-sutural thread. 



T. triserialis var. intermedia Dall. Two rows of not prominent apically 

 inclined nodules, a smaller undulated thread between them, a still smaller one 

 behind the suture; undulations of the medial thread opposite the interspaces 

 between the nodules; no ribs: young with proportionally stronger nodules; 

 shell rather elongated. 



T. sarissa Dall. Three rows of strong tubercles, with their longest slope 

 toward the middle of the whorl, posterior row largest, anterior next in size, the 

 third close to the posterior row and smallest; suture not bordered by threads 

 and nearly invisible. 



B. With two principal spirals. 



T. colon Dall. Two spiral rows of equal nodules overrun and connected by a 

 sharp line; a very fine undulate line on each side the suture; no ribs, whorls 

 very short and flat; base flatfish; shell slender and small. 



