414 On Marine Shells from Henderson Islana. 



almost like folds, such as occur in the genus Mitra, and the 

 lower one is formed by the edge of the columella bordering 

 the canal. 



Tritonidea dlfficilis. (PI. IX. fig. 2.) 



Testa elongata, pallide lilacea, hie illic fusco maculata ; anfractus 

 8?, convexiusculi, longitudinaliter costati et spiraliter lirati, 

 liris supra costas leviter tuberculiformibus, inter liras spiraliter 

 striati, lineis incrementi tenuibus inter costas sculpti; anfr. 

 pennltimus et ultimus costis cireiter 16 instructi ; in anfract. 

 superioribus costae sensim rariores ; ultimus in medio convexi- 

 usculus, infra contractus, liris spiralibus ad 16, quam costis 

 gracilioribus, ornatus ; costse infra medium sensim evanescentes ; 

 apertura brevis, longitudinis totius 3 paulo superans ; labrum 

 extra late incrassatum, quasi varicosum, intus liris cireiter un- 

 decim intrantibus, ad marginem denticulatum ; columella supra 

 arcuata, denticulo prope labrum munita, prope medium incisuram 

 unicam monstrans, callo definito tuberculis 5-6 instructo amicta ; 

 canalis anterior brevis, obliquus. 



Longit. 19, lat. 8 mm. ; apertura 6-5 longa, 2*5 lata. 



I have only seen one specimen of this species, which does 

 not appear to approach very closely any of the known forms. 

 The purple apex being worn, the number of whorls is rather 

 uncertain, but probably is about eight. The broad thickening 

 of the labrum has a large brown blotch above the middle and 

 a smaller one below, and the spire is blotched at intervals 

 with the same colour. The notch on the columella is only 

 slight, but is probably a constant feature. 



This and the following species are placed in the genus 

 Tritonidea for want of a better location, since this group and 

 Cantharus require urgent revision. 



Tritonidea rosacea. (PI. IX. fig. 3.) 



Testa parva, fusiformi-ovata, pallide rosacea; anfractus 6?, con- 

 vexiusculi, costis 6eptem crassis, albidis, rotundatis instructi, 

 liris spiralibus alternatim majoribus (in anfractu penultimo 8-9, 

 in ultimo cireiter 18) cincti, inter liras tenuissime spiraliter striati ; 

 costa? in anfr. ultimo ad basim continua?, paucaa antice conspicue 

 nodulosa? ; apertura parva, ringens ; labrum incrassatum, denti- 

 bus validis quatuor intus armatum ; columella in medio intus 

 incisa, callo definito induta, supra marginem externum tuberculis 

 quatuor munita ; canalis anterior brevis, obliquus. 



Longit. cireiter 13, diam. 6 - 5 mm. ; apertura intus 5 longa, 2 lata. 



Characterized by its rosy colour, strong costa?, and dentate 

 aperture. There is a slight sinus above the posterior denticle 



