128 , i^'^y- 



same holds good in a less degree with regard to that of the nymph) ; 

 my figures of that part have accordingly been made from examples 

 dissected out. The mandibles are notoriously difficult to delineate in 

 a satisfactory way ; they are asymmetrical to begin with, and each one 

 presents a new form with every change of position, however slight : 

 isolated figures taken from different species and from different points 

 of view" are therefore of no use for comparative purposes. My figures 

 of mandibles are almost all drawn from heads mounted in balsam, and 

 represent these organs nearly in situ, as seen from above and below ; 

 in some instances their position may have been slightly altered by 

 pressure — the only difficulty experienced in carrying out the principle 

 of uniformity which I have indicated as so desirable. The strong 

 hairs which are so prominent on some of the mouth parts appear to 

 be constant as to number, but they cannot be relied on much, because 

 they are easily lost, and few specimens can be found which do not 

 show cicatrices or traces of detached hairs. 



Further general remarks are reserved to the end of the series. 



The first Section to be noticed is that of Molanna, containing the 

 single genus Molanna, of which two species are found in Britain, M. 

 angustata and M. pulpata. The latter insect occurs commonly in the 

 North of Scotland, but, so far, nothing has been ascertained about its 

 earlier states. 



1. — Molanna angustata. Curt. 



Larva elongate ; head small, long-oval ; prothoras small, transverse, little 

 broader than the head ; nieso- and mctathorax both large, sub-quadrate, each broader 

 than the segment preceding it. First abdominal segment broader than the meta- 

 thorax, and almost as broad as any of the succeeding segments ; the abdomen, which 

 is rather compressed dorso-ventrally, is moderately large, and tapers very slightly 

 towards the extremity, only the last segment being conspicuously narrower. 



Head above witli a limited number of long hairs ; clypeus comparatively broad ; 

 " triangular " piece large and broad ; antennse placed on a rounded base, long, cylin- 

 drical, terminating in a hair. Labrum transverse, convex ; fore-margin with two 

 slender processes arising from the middle, and two long, blunt, inturned processes 

 on either side ; four discal and two lateral hairs ; and on under-side six adpressed 

 spines arranged in two rows towards the lateral margins, the points of the spines 

 being turned inwards. Mandibles elongate (see figs.). Maxillje with the basal part 

 elongate ; blade small, tapering ; seen from above, with a few spines ; palpi tapering, 

 3-jointcd, second joint longest. Labium long, conical, numerous hairs beneath ; 

 palpi small, apparently 2-jointed. 



Prothoracic plate slightly excised in front, rounded behind, and indistinctly 

 bilobcd. Mesonotum subquadrate, the hind angles not sharply defined ; the middle 



