HTBOLITHES. 169 



HEPTALASMI8. Leach. ('ETrra, hejita, seven ; eXaa-fxa, elasma, 

 plate,) A small shell resembling Pentelasmis, from whicli it 

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

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

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



■ Octolasmis, the appearance of seven valves being caiised by the 

 scuta being entirely or partially divided into two segments. M. 

 Darwin has decided not to retain either of the names^ implying 

 the apparent number of valves but to name the genus. Diche- 



• LASPis. Eoe. D. Warwickii, PL ii, fig. 41. 



HEECOLES. Montf. A microscopic shell, appearing from De 

 Montfort's figure to resemble Tkochtts Impenalis in shape. 



HEEIOJS". Montf. Lektictjlina, El. Microscopic. 



HEEMAPHEODITA. Bl. The third sub-class of Paracepha- 

 lophora, El. divided into, Sect. 1, symmetrical, containing the 

 orders Cirrobranchiata and Cervicobranchiata ; Sect, 2, nonsym- 

 metrical, order, Scutibranchiata. 



HEEMES. Montfort, 1810. A genus composed of CoKirs 

 Nussatella, Auct. and other elongated, cylindrical, striated 

 species, PI. xxi. fig. 460. 



HETEEOBEANCHIATA. Bl. The fourth order of the class 

 Acephalophora, Bl. containing no testaceous moUusca. 



HETEEOPODA. Lam. The fifth order of the class MoUusea, 

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

 naria, fig. 488. 



HETEEOSTEGINA. D'Orb. A genus of microscopic Eorami- 

 nifera. 



HIATELLA. Dan din. Earn. Lithophagidse, Lam. A genus 

 composed of species of Saxicava, Auct. which have sharp, angu- 

 lated, posterior ridges, a circumstance which occurs to many 

 species in a young state, which afterwards become rounded ©fi*. 

 Hiatella biaperta. PI. iv. fig. 95. 



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

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

 PL xxi. fig. 458, 



HIBOLITHES. Montf. A genus composed of species of Belem- 



