MUSEUM OF COMPARATIVE ZOOLOGY. 215 



where this line crosses the varix there is merely an angle, at others we find a 

 hook or recurved even sigmoid spine, which, however, does not retain its origi- 

 nally excavated character. In species of the other type, like T. arcuatus Hinds, 

 T. duplicatus Sovverby, T. japonicus A. Adams (very probably all varieties of 

 a single species), T. fistulosus Brocchi, and the one about to be described, we 

 find that the varix commences with and at the tube, though mostly developed 

 beyond it, giving the completed shell the appearance of having had its tubes 

 bent backward. Now in the common Mediterranean T. tetrapterus Bronn 

 (+ T. Sowerbyi Auct.) a sinus was observed and is figured by A. Adams, though 

 there are no permanent processes on the mantle-edge. It is absolutely certain, 

 however, that at times when the shell is being secreted there must be a sinus 

 in the mantle-edge analogous to that in Drillia, and the subtubular projection 

 at the bottom of the sinus observable in many Drillias is analogous in its for- 

 mation to the tube of Typhis. Both are doubtless avenues of escape for effete 

 matter voided from the intestine. In Typhis of the typical section (like 

 T. tetrapterus) there must be in the portion of the mantle which secretes this 

 part of the shell an alternation of functions daring the period of growth from 

 one varix to another. In the other section (which may be called Trubatsa) 

 there is only a resting time and a renewal of identical functions. 



It is of course true, that, in taking a general survey of the genus, certain 

 somewhat intermediate species may be found ; but this is what we must ex- 

 pect everywhere when we know all the species of any genus in their numer- 

 ous variations. The worker who has the interest of science really at heart 

 will in such cases avoid undue subdivision, either specific or generic; and 

 when he finds that a division is advisable, he will give, not merely a few 

 lines of description in more or less canine Latin, but a differential description 

 showing, not only the characters on which he relies, but the way in which 

 they differ from the characters exclusive to other groups, and to groups of less 

 value, such as species. If all the specific characters were eliminated from his 

 consideration, and he had been obliged to give differential diagnoses, it is 

 likely that the author of the eleven unnecessary synonyms of Typhis would 

 have paused, and probably thought better of it. 



The length of both the tube proper and the tubular canal is greater when 

 it is first formed than later. It seems to be soon dissolved by the water, or 

 broken off. The last tube, until it is broken, is therefore always longer than 

 the others. Specimens from the quiet abyssal waters occasionally preserve the 

 tubes, or part of them, in a way to make this evident. 



There is only one species of Typhis known in the recent state from the 

 Antillean region. A species of Murex or Eupleura (M. cancellata Sby.) is 

 reported by Krebs, and has been catalogued as a Typhis by Try on. I doubt 

 whether it can properly be referred to this genus. In 1849 Sowerby described 

 a fine species, T. alatus, from the Miocene Tertiary of St. Domingo (Geol. 

 Journal, VI. p. 48, pi. x. fig. 4), which is so much resembled by the Typhis 

 expansus of the junior Sowerby, a recent species described without habitat in 

 1874, that I cannot help suspecting that they are the same, and that the species 



