HIATULA. 161 



forming an internal groove. H. tricostata, Sw. Sow. Gen. 

 fig. 6." 



HEMITROCHUS. Sw. A sub-genus of Geotrochus, Sw. H. 

 heemastoma. Sw. p. 331. 



HEPTALASMIS. Leach. ('Birra, hepta, seven ; eXaafia, elasma, 

 plate) A small shell resembling Pentelasmis, from which it 

 differs in the number of valves, being composed of seven valves 

 according to Leach, and of eight according to Gray, who counts 

 the dorsal valve, which is jointed, as two, and names his genus 

 Octolasmis. Fig. 41, H. Warwickii. 



HERCOLES. Montf. A microscope shell, appearing from De 

 Montfort's figure to resemble Trochus Imperialis in shape. 



HERJON. Montf. Lenticulina, Bl. Microscopic. 



HERMAPHRODITA. Bl. The third sub-class of Paracephalo- 

 phora, Bl. divided into, Sect. 1, symmetrical, containing the 

 orders Cirrobranchiata and Cervicobranchiata ; Sect. 2, non-sym- 

 metrical, order, Scutibranchiata. 



HERMES. Montf. A genus composed of Conus Nussatella, 

 Auct. and other elongated, cylindrical, striated species. Fig. 

 460. 



HETEROBRANCHIATA. Bl. The fourth order of the class Ace- 

 phalophora, Bl. containing no testaceous mollusca. 



HETEROPODA. Lam. The fifth order of the class Mollusca, 

 Lam. This order contains but one genus of shells, viz. Carinaria, 

 fig. 488. 



HETEROSTEGINA. D'Orb. A genus of microscopic Foramim- 

 fera. 



HIATELLA. Daud. Fam. Lithophagidse, Lam. A genus com- 

 posed of species of Saxicava, Auct. which have sharp, angulated, 

 posterior ridges, a circumstance which occurs to many species 

 in a young state, which afterwards become rounded off. Fig. 95, 

 Hiatella biaperta. 



HIATULA. Sw. A genus proposed to include those species of 

 Oliva, Auct. which have widened apertures. Ex. 0. Subulata, 

 fig. 458. 



M 



