388 AJhctny Museum Records. 



ttje Sahai-an Leptocoelia fiahellites, Conrad, is doubtful, while the 

 Hoirialonotus lierscheli from Tassili appears to me to belong to a 

 far more rounded form than our South African H. herscheli, and 

 reminds me of the Rhine species H. ohtusa, Saudberger. Spiro- 

 phyton, too, occurs with the marine forms in the Sahara, as in the 

 Eifel^ 



Cat. No. 1457. Donor : Mr. A. G. Bain ; no locality. 



Honialonotus hippocampus, nov. sp. 



PI. IX., Figs. 5a, 5b. 



This form is distinguished from the H. ItersclieJi type by the 

 sharply rriangnlar shape and by the flatness of the glabella region. 

 Mostly small forms. 



The following are the characters of the head, the only part 

 w^hich we know: — 



Form triangular, with margins straight ; broader than long 

 in the propoi'tion of eight to five. Cheeks very swollen ; free 

 portion almost vertical and out of sight when viewed from above ; 

 the flattened space at the base of the glabella which occurs in H. 

 herscheli is fairly well seen. Glabella not well defined ; broadest 

 at base ; indented between the eyes and blunt in front ; the upper 

 lobes are distinct, but the basal and middle ones are not ; they are 

 represented by a flattened surface as if an inflation had fallen in, 

 and in the centre there is a slightly elevated ridge. The neck 

 ring is separated from the head by a strong furrow, and on either 

 side bears near the margin two strong spines, supported on a com- 

 mon swollen base. Eyes small, lunatelj" oval, in the internal cast 

 borne on a prominent eye-stalk, which projects outwards and 

 a little forwards from the inflated cheek. Facial sutures distinct, 

 beginning at the front margin, sloping outwards to the eye, and 

 thence outwards and a little backwards to near the outer margin 

 where it turns round, rendering the posterior portion of the free 

 cheek spine-shaped. In-turned lower margin projects beyond the 



'E. Hang, in F. Foureau, Mission Saharienne, Paris. 1905, p. 776, 

 PI. XIV., figs, 1-6. 



