— 25 - 



The sac-sh;ipo(l ^land of Phi/mnfens docs no prosciit a 

 typical example of Stein's cells, as in sections the nnclei <»f 

 the cells of the deferent canals ar(» discerned only Nvith 

 difficnlty in the matrix layer [accordini!: to Nassonov (17) 

 the nuclei and j)rotoplasm of these cells may in sonic cases 

 become altoi^ether reduced]. \'osseler has described in Ocda- 

 leiis senc</alensis Krss an orj^fan which is similar in micros- 

 copical structure, and to which he ^'ave the name of odori- 

 ferous ^land. It is situated in the pronotuni under the skin 

 in the form of a triangular sac capable of aversion outside. 

 This gland Vosseler compares with the odoriferous gland of 

 For fie It hi. 



Besides the sac-shaped abdominal gland described above, 

 I have found in Pliymateus two more glands on the dorsal 

 surface of the fold between the second and third abdominal 

 segments. Each organ presents a layer of glandular cells lying 

 under the hypoderm, which is covered by folded chitin 

 (fig. 11, D, N, N; fig. 12, D). The latter is pierced by chitin 

 canals, which is clearly visible in preparations with the cuti- 

 cle exfoliated. The canals lead into the gland-cells (fig. 12 A) 

 the secretion of which falls out in the form of grains (fig. 11, S), 



This is also a Stein's gland, but more primitive than the 

 sac-shaped abdominal gland, as it presents only a glandular 

 area formed by Stein's complexes of cells closely adjoining- 

 one another. Similar formations to those dorsal glands are to 

 be found in other Orthoptera, namely, in cockroaches. Mine hi n 

 (15, 16) and Kulvetz (14) have described in c? and ? of Peri- 

 planeta orientalis paired odoriferous glands in the membrane 

 between the tergites of the V and VI abdominal segments. 

 Nassonov (17) has given a more detailed description of their 

 microscopical structure and referred them to the group of 

 sac-shaped Stein's glands. 



I should consider the dorsal glands of Pliyviateus as homo- 

 dinamous to the dorsal odoriferous glands ^) of Periplaneta 



') Ruth M. Harriosn (10) has found in both sexes of Pcriidancta an 

 unpaired sac-shaped odoriferous gland, opening on the median line of the 

 body between the sternites of the VI and VII segments of the abdom<Mi, 

 and Bordas (2) considers the organ in the shape of a retort opening under 

 the genital aperture of Periplanota orientalis and P. americana as an 

 odoriferous gland. 



