MUSEUM OF COMPARATIVE ZOOLOGY. 209 



lum of Sipho or Boreotrophon. Favarlia, which is nearest in form to this 

 among the Murices, has a muricoid operculum with its nucleus not apical. 



Dentition like that of typical Murex, not resembling Muricidea, Ocinebra, or 

 Trophon. 



Superficies of the shell with a cellulose or finely vermiculated cretaceous white 

 layer ; beneath this chalky layer a harder shell-substance, sometimes colored. 

 Epidermis seemingly absent. 



Canal short, recurved, always open; aperture denticulated in the adult. 



The soft parts of a specimen of A. scalarioides var. paupercula Adams, taken 

 at Key West by Hemphill, were white with very distinct black eyes. The ten- 

 tacles were small and close together, the eyes situated on their outer sides 

 half-way toward the tip. The foot is large for the size of the animal, rounded 

 behind, double-edged in front, and auriculated at the anterior corners. As far 

 as one could judge from the contracted alcoholic specimen, the auriculation 

 must have been very marked and the anterior median indentation deep. The 

 proboscis moderately long, the radula long but very small, its formula 1+^4-1. 

 It much resembled that of M. trunculus and M. brevispina as figured by Tro- 

 schel in his Gebiss der Schnecken. There were the usual two gills on the left 

 side. The oesophagus was rather long, with no post-oral dilatation, and much 

 contorted. There seemed to be a small appendix to the right margin of the 

 siphonal extension of the mantle. 



The shell of this species when quite young looks like a small inflated Boreo- 

 trophon. As it gets older, a tendency is often exhibited in two of the normal 

 six varices to grow bigger than the others, beside which the intermediate part 

 of the whorl actually becomes somewhat flattened. A specimen of this sort, 

 especially if the flattening is pronounced, as it sometimes is, looks much like a 

 large white Aspella hastula, and one such was described by Dunker as Ranella 

 lamellosa. For this state or stage, sometimes permanent, I reserve the varietal 

 name lamellosa. 



Generally the second stage passes, later on, into what may be called the nor- 

 mal form, which is not flattened but muricoid or like a small Tritonium. This 

 I call variety paupercula, as it is what was described as Murex pauper cuius by 

 Adams, and later as a Triton by Recluz. 



This may be stout or slender, and is usually pure white. The slender form 

 is apt to have the spiral lines stronger. When very long and with some 

 touches of light brown on the under layer of the varices it becomes variety 

 obeliscus, described as a species by A. Adams. This may be the same as 

 Murex alceatus Kiener (if that is not a Favartia), and is certainly the shell 

 figured under that name by Reeve. 



The typical form is that from the Mediterranean, which, in a full series, I find 

 to be generally more elevated, with rounder whdrls, less prominent varices, and 

 obscurer spirals. Still there are some Mediterranean specimens exactly like 

 the Floridian variety paupercula. Blainville's specific name seems to be gen- 

 erally accepted, and I have used it, but have not been able to consult the original 

 work. Monterosato adopts Bivona's specific name and separates the shell under 



vol. xviii. 14 



