532 Mr. D. Sharp and Mr. F. Muir on the Comparative 
and slightly curved, the bases meeting on dorsal and ventral sides, 
Basal-piece, forming a large sclerite on ventral face, with its edges 
turned up along sides and base, meeting together where lateral 
lobes are articulated. Internal sac undifferentiated. 
In the genus Parnis the lateral and median lobes are very small, 
the basal-piece large, and forming a long chitinous and slightly 
curved tube. The internal sac undifferentiated. Figs. 127 and 
127a Pl. LXIII, are of P. luridus. It has a curved chitinous 
spine (c) on the ventral aspect of the median orifice. 
Family DERODONTIDAE. 
Form examined: Lavricobius erichsoni Ros., Macugnaga. 
Fig. 128 Pl. LXIII. 
Laricobius erichsoni (Pl. LXIII fig. 128). 
Trilobe form. Median lobe large, fairly wide, and pointed at tip, 
formed of a large chitinous sclerite on dorsal aspect, membranous on 
ventral face; median orifice on ventral aspect before tip. Lateral 
lobes large, round at tips, excavate at base on inner side where 
they envelop the base of the median lobe. Basal-piece large, formed 
by a shield shape sclerite on ventral aspect, emarginate at base, and 
membranous on dorsal face. Internal sac undifferentiated. Closely 
allied to Mycetophagus q.v. 
Family CIOIDAE. 
Forms examined: Cis boleti L. and C. nitidus Herbst. 
England. 
Figs. 129 and 129a Pl. LXIITI. 
Cis boleti (Pl. LXIII figs. 129, 1292). 
Median lobe long, slender and tubular, with median orifice at 
apex. Lateral lobes of tegmen forming a large plate on the ventral 
aspect, turned up along the lateral edges, and the distal end flattened 
and slightly expanded, forming a median, emarginated process and 
a rounded process on each side of it ; basal-piece small, chitinous 
on the ventral aspect. Internal sac not dissected out, but apparently 
not differentiated. 
C. nitidus is on the same plan, but the large plate formed by the 
tegmen is cleft down the distal half. 
The ventral aspect of the tegmen is an important 
feature of this family. 
