9 



being placed in two rows with their distal points meeting at an angle, there being eight of 

 these double rows on the calyx walls or over the tentacle bases, to correspond with the number 

 of tentacles in the alcyonoid polyp. 



This is not always a good generic character, but may be used in combination with 

 others in formulating definitions for the genera of the JSfuriccidcc. 



There still remain a number of muriceids with simple spindles for their type of spicule, 

 and these are too varied in character to be placed in a single genus, even after all of those 

 with spindles en chevron have been provided for. These all agree in having spindle-form 

 spicules only, without a noticeable admixture of other types, although there is often a considerable 

 modification of the spindle in the way of enlargement or in being more slender, or in being 

 stouter, or in being arranged in layers in the coenenchyma. Finally there are some genera in 

 which the form of the colony seems of use in generic distinctions. 



By the means above indicated it is possible to divide the very numerous species of this 

 large family into generic groups that seem to be fairly natural ones. The writer believes that 

 the main purpose in forming genera is to facilitate identification and classification. Our knowledo-e 

 of the lower invertebrates is still far too fragmentary to permit us to indulge the hope that 

 our work as systematists will really serve to express, in final form, the actual relationships of 

 any large groups of animals. While a natural classification is a "consummation devoutly to be 

 desired" we are not yet, is seems to me, in sight of it. Meanwhile we can use our o-enera as 

 convenient names under which we can group species for practical purposes, being careful, however, 

 not to abandon long established genera without good reason. Neither does it seem desirable 

 to establish new genera so long as legitimate characters can be drawn from the type species of 

 existing genera whereby the latter may be retained although modified to include new forms. 



Key to the genera of Muriceid.e as used in this work. 



Calyces bilabiate (Muricea) ' 



Calyces not bilabiate. 



Spindles arranged en chevron on calyx walls or tentacle bases. 

 Spindles en chevron on calyx walls only. 



Calyx with crown of points of Acanthogorgia type Acanthogorgia 



Spindles en chevron on both calyx walls and tentacle bases. 



No crown of points. Spicules all regular spindles Anthomuricea 



A crown of points consisting of spicules with radiating foliaceous 



expansions (Paramuricea) 



A crown of points consisting of regular spindles Muricella 



' Generic names enclosed in brackets indicate that such genera are not represented in the Siboga collection. 



SIBOGA-F.XPKUITIK XIll/'. 



