64 BULLETIN OF THE 



double row of crowded narrower ones in front of the suture separated by a 

 depression; surface wholly finely spirally striate with (30-32) crowded narrow 

 straight costae passing clear over the whorls on to the base ; pale brown. Lon. 

 21.0, lat. 4.5 mm., whorls 12. Acus benthalis Dall. 



Whorls flat ; band smooth, convex ; sides with four flat spirals decreasing 

 forward from the band to the suture, and others still finer on the base; trans- 

 verse sculpture obsolete except on the earliest whorls except faint incremental 

 lines ; shell porcelain-white, polished. Lon. 15.0, lat. 3.3 mm., whorls 13. 

 Acus Rushii Ball. 



This tabulation is the result of a study of a large collection of material l'rom 

 all points of the region. The number of forms is larger than was anticipated, 

 knowing the variability of the species of this group. 



Before proceeding to enumerate and describe the species obtained by the 

 Blake, a few words on the other species may be of interest. The typical 

 Acus concavus has been received only from the coast of the two Carolinas. The 

 variety vinosa hays been obtained in from two to thirty fathoms along the coast 

 from Hatteras to Florida. It is abundant in Sarasota Bay and Charlotte Har- 

 bor, West Florida, frequenting the fucoids with finely divided fronds, the 

 color of which it mimics. The operculum is somewhat lozenge-shaped, with 

 an apical nucleus. The tentacles are mere eye-pedicels, and when not especially 

 active the animal looks as if the eyes were sessile on the front of the head. 

 The siphon is more than half as long as the foot, which is squarely truncate 

 in front and extends far in advance of the eyes. The front margin appeared 

 to be double and the tail was bluntly rounded. The soft parts were entirely 

 white in the white variety. The proboscis is extremely large and internally 

 corrugated. There is no radula, and there are no mandibles, according to 

 Stimpson's notes. 



The common Terebra of our coast is the well-known Acus dislocatus of Say. 

 It extends from Maryland to Florida, Texas, Venezuela, the Bahamas, and the 

 Antilles. It has a number of synonyms, of which the most common are T. 

 rudis Gray and T. Petitii Kiener. It is found fossil in the Miocene and Plio- 

 cene of the Southeastern United States. Stimpson states in his unpublished 

 notes that there are no jaws nor radula, but in the constriction of the pro- 

 boscis (which is hourglass-shaped when half withdrawn) he found a series of 

 grooved prickles. I suspect these were the poison fangs of the animal, which, 

 as in some other Toxoglossa, are not set upon a radular band. If this suspicion 

 be confirmed, this species will probably have to be removed from Acus (charac- 

 terized by absence of teeth) and referred to Hastula. 



The proboscis of this species when extended is of portentous magnitude. 

 It is extruded base first like the rostrum of Cyprcea. It is very muscular and 

 internally corrugated, funnel-shaped, and biggest at the distal end, which encloses 

 the victim, who is squeezed, smothered, and sucked to death simultaneously. 

 The stomach is considerably smaller than the cavity of the proboscis, and is 

 connected with it by a narrow oesophagus. From the posterior end of the 

 January 18, 1889. 



