160 
caecal pockets, and the caecal structures themselves were but briefly 
treated. Dr. Glasgow hopes to continue these studies, and will be very 
glad to examine fresh specimens, living, if possible, of any additional 
species; in the meantime he has very kindly placed at my disposal the 
unpublished details thus far obtained by him on this subject. 
In the Halydinae, genus Brochymena, he found between the third 
stomach and the rectum an elongate intestinal tract bearing four equal 
and equidistant rows (two opposite pairs) of numerous close-set finger- 
like caecal pockets, about 400 in each row. In all the Pentatominae, 
Scutellerinae, and Graphosomatinae examined, he found the same struc- 
ture uniformly present, except that the number of pockets in a row was 
less, varying from 70 to 220. The largest numbers in the Pentatominae 
were in Nezara (220), Euschistus (190), and Murgantia (160); the 
smallest, in Solubea (70), Hymenarcys (75), Cosmopepla (75), and 
Peribalus (90). Thyanta, Mormidea, Coenus, and Proxys were interme- 
diate (110-125). The Graphosomatinae were represented by Podops . 
cinctipes (75-80), and the Scutellerinae only by Homaemus proteus (105— 
110). 
A second type of this structure was found in the Cydnidae, Coreidae, 
Pyrrhocoridae, and certain Lygaeidae. Here there is only one pair of 
opposite rows, without the slightest trace of the other two of the first 
type. The number in each row varied greatly in different genera. In 
the Cydnidae the number was not large—65 in Sehirus (Cydninae) and 
75-90 in Thyreocorinae; in the Coreidae there is a quite regular descend- 
ing series, from 775 in Archimerus and 650 in Metapodius to 155 in 
Catorhintha, 125 in Alydus, and none at all in Stachyocnemis and the 
Rhopalinae ; and in the Pyrrhocoridae, Largus had 135, while Dysdercus 
had very few—only six in the female and none at all in the male. The 
Lygaeidae show a decided tendency to reduction and specialization. In 
the Pachygronthinae there are again two rows; in Oedancala dorsalis, 31 
in each row, rather loosely spaced and oval; in Phlegyas abbreviatus, 
about 29, long and narrow and closely placed in two short rows, but the 
last pair in the female is greatly enlarged. In most other Lygaeidae and 
in Berytidae [= Neididae] a third type of this structure appears, evi- 
dently a modification of the previous type. In this type there are very 
few pockets, more on one side than on the other, and the pockets of each 
side are bunched together in one or two groups on a common basal con- 
nection. In Myodochinae and Blissinae there are on one side two groups, 
each of 3-12 pockets; and on the other side, only 2-7 pockets in all, 
usually in a single group, rarely in two. In the Berytidae [ — Neididae] 
there is only a single group on each side, the number of pockets on each 
side in Jalysus spinosus being 6 and 9 respectively in the example studied. 
In making these studies, often many individuals of a species were 
examined, and the variation within a species was found to range from 
4 to 18 per cent. of the total number, being usually about 10 per cent. 
In the remaining groups examined, related to those mentioned, as 
well as in all the other Heteroptera, the structure was found to be entirely 
