38 



Annals of the Carnegie Museum. 



ielus all having this type, while Basilicus is the only member of the group 

 with the Niobiform suture. On the other hand those trilobites with an 

 undi\ided hypostoma usually have the Niobiform suture, it being present 

 in Ogygia, Ptychocheilus, Asaphelina, Niobe, Symphysurus, IlIcBminis. Ni- 

 lens, Barrandia, Ilomalopteon, and Platypeltis A few genera which have 

 the undivided h>'postoma do have the Isoteliform suture, namely, Mega'as- 

 pis, Megalaspides, Asaphellns (as here restricted) and Ogygia corndensis, 

 a species which Salter and Brogger have both said was not an Ogygia, 

 but which they could not refer to any existing genus. Taking into con- 

 sideration these facts, it does not seem possible to place Asaphellus as a 

 subgenus of Niobe, or to place in one subgenus species having both types 

 of suture, as Brogger has done in emending Asaphellus so as to include 

 Asaphus affinis McCoy, Ogygia desiderata Barrande, and other species 

 which are here referred to a new subgenus of Niobe.''- 



6 7 



Fig. 6. Asaphellus homfrayi (Salter). Outline of compressed specimen^ 

 After Salter. 



Fig. 7. Hemigyraspis affinis (McCoy). Outline of a somewhat distorted 

 specimen. After Salter. 



The genus Asaphellus is here restricted to trilobites having the same 

 characteristics as the type species, Asaphus homfrayi Salter. The facial 

 suture is entirely on the dorsal surface as in Isoteliis, the glabella is smooth 

 and hardly defined, also as in Isotehis, but there is a median pustule on 

 the glabella, the hypostoma is not forked, and the thorax has a narrow 

 axial lobe. There is no neck ring, the neck furrow is extremely shallow, 

 and the spines at the genal angles are long and nearly circular in cross 



>"Ueber die Ausbildung des Hypostomes bei einigen Skandinavischen Asaphi- 

 den," Bihang till K. Svenska Vet. Akad. Handlingar, Band XI, i886, p. 55. Also his 

 article on the "Euloma-Niobe Fauna," Nyt Mag. for Nalurvidensk, Band XXXV,. 

 1896. 



