MUSEUM OF COMPARATIVE ZOOLOGY. 3 



projected, and had largely carried out at the time of his premature 

 decease. 



In the course of this Report the writer has freely criticised the litera- 

 ture which he was required to consult, not with any desire of fault- 

 finding, but because frank and free criticism is, it seems to him, the 

 most desirable way of getting at the truth. During Mr. Tryon's life- 

 time the writer felt obliged on several occasions rather sharply to 

 criticise ' the execution of some parts of that gentleman's Manual, and 

 it gives him pleasure to say, now that Death has intervened, that this 

 criticism never interrupted the friendly relations which mutually ex- 

 isted and continued to exist. Mr. Tryon, without entering into contro- 

 versy, took steps to remedy such of the faults as he felt to be justly 

 criticised, and a comparison of the later volumes of the Manual with 

 the earlier ones will sufficiently illustrate the result. The work is 

 important, and almost indispensable, while from its very nature it is 

 especially liable to minor inaccuracies. For this reason the writer has 

 not eliminated any of the criticisms or corrections from his manuscript 

 prepared during Mr. Tryon's lifetime, and which now is printed. He 

 believes that his friend would prefer that all just and fair corrections 

 should be made, and that the science to which he was thoroughly de- 

 voted should thus be advanced. Well aware that he himself may in 

 turn offer a fair target for the critic, the writer invites corrections which 

 may suggest themselves to other malacologists. 



A summary of the numerical results of this investigation into the 

 Antillean and Gulf fauna will be found at the end of this paper, where 

 it is placed in order that it may express the latest and most accurate 

 figures. These data are, as every one knows, liable to be slightly 

 modified in the course of printing and proof-reading. 



In this Report all dimensions are given in millimeters ; all tempera- 

 tures are bottom temperatures, and expressed in degrees Fahrenheit. 

 The measurements of a shell are made parallel with the axis, the curve 

 of the profile not being taken into account. The term longitudinal in 

 description is equivalent to spiral, and indicates a direction parallel 

 with the coil of the whorl. The term transverse refers to sculpture 

 crossing the whorls in general parallelism with the longitudinal central 

 axis of the whole shell. The nucleus is the larval shell, be the same 

 large or small. The apex of the spire is considered to be the posterior, 

 the end of the canal to be the anterior end of the shell, and all terms 

 indicating direction are to be understood in harmony with this defini- 

 tion. Right and left, when used, are used as if the animal were crawl- 



