62 BULLETIN OF THE 



Super-Order PROSOBRANCHIATA. 



Order PECTINIBRANCHIATA. 



I have, in sum, followed Dr. Fischer in the arrangement of this group, mod- 

 ifying slightly the values and some details. I heartily concur in his expression 

 of opinion, that a final arrangement of the groups included in this order awaits 

 much fuller knowledge of the animals than we now possess. 



The groups, hardly suborders, based on the dentition, are not of equal value. 

 Toxoglossa and Rhachighssa are certainly more closely linked than either or 

 both with Tceuiogbssa. The latter leads the way toward Rhiphidoglossa. The 

 place of Gymnoglossa is doubtful. 



Super-Family TOXOGLOSSA. 



The facts now known warrant us in believing that the teeth in this group 

 represent the uncini of other groups, while the middle part of the radula is 

 only known, so far, to occur in Spirotropis. On the other hand, the losses in 

 Rhachiglossa have been at the edges instead of the middle, and the uncini and 

 sometimes the true laterals or admedian teeth are the ones which are absent. 

 Probably a fuller knowledge of the dentition will completely bridge the gap 

 now existing between the two groups, and afford us examples of every degree 

 of modification. 



In separating this group into families I have adopted the groups rated as 

 subfamilies by Dr. Fischer, merely assigning them a somewhat higher value. 



Family TEREBRID^E. 

 Genus TEREBRA (Adanson) Lamarck. 



Of this genus the type is T. subulata Linne", and no species known to belong 

 to the typical section are so far reported from the region we are discussing. 

 The subdivisions of the genus which are represented are Euryta H. & A. Adams, 

 Subula Schumacher, Hastula (Adams) Troschel, and Acus (Humphrey) Tro- 

 schel. As until the dentition of all our species is examined the place they 

 should occupy will be uncertain, the reference here to the subgenus in some 

 cases is only provisional. 



Euryta aciculata Lamarck is well known, and has been received from 

 Venezuela and the Bahamas by the National Museum, as well as from the 

 Antilles. 



Hastula hastata Gmelin (+ casta Hinds and obesa Poulsen) has been re- 

 ceived from Florida, Aspinwall, and the Bahamas, beside the Antilles. 



