358 . MR. ROBERT SHELFORD ON 



Fig. 58. Ti/Iocephalum ludificans, sp. ii. Ti/pe. Section tlivouffh an example in the 

 tissues of the Ceylon Pearl-Oyster in Professor Herduian's collection. 

 Slide 9i of Professor Henlman's series, a., armature of collar. This shows 

 the myzorhynchus of " Ti/locephahun " form, due to the posterior face 

 {m.p.) being contracted and its surface thrown into folds and the anterior 

 face {m.a.) stretched. Compare the adult Tijlocephala in figs 61 & 62, 

 and also the species shown in tig. 65. X 70. 



Fig. 59. Section through another example of the same species, showing the " Cepha- 

 lohothrium "-form of mj'zorhynchus ; here the posterior surface of the 

 niyzorhyuchus {m.p.) is tense, and its anterior surface {m.a.) is thrown into 

 folds, a, armature of collar. (Compare the adult worm in fig. 66.) X 70. 



Fig. 60. An adult worm, which may be the adult of Tijlocephalum ludificans, 

 from the spiral intestine of Aetohatis narinari. X 6. From Dr. Shipley's 

 collection. 



Plate XLVII. 



Fig. 61. The head of the worm shown in fig. 60, viewed as a transparent object. 



m., myzorhynchus ; s, s', s", threeof the four marginal suckers; a., armature 



of collar ; seg., first proglottides. X 70. 

 P^ig. 62. The same, in section ; letters as above. X 70. 

 F'ig. 63. Armature of collar of same, about point a in fig. 62. X 1000. 

 Fig. 64. Penultimate segment of same. 

 Fig. 65. Head of Tyloceplialum uarnak from Tr,ygon uartialc. From a slide in 



Dr. Sliipley's collection, my., niyzorhj'nchus, which here is fully protruded ; 



ma., anterior face of same; inp., posterior face; s, s', s", s"', the four 



marginal suckers. X 45. 

 Fig. 66. Head of Cephalobothrmm aetohatides from Aetohatis narinari. From a 



specimen in Dr. Shipley's collection. Letters as above. X 70. 



19. Mimicry amongst tlie Blattidse ; with a Revision ol: the 

 Genus Prosoplecta Saiiss., and the Description of a new 

 Genus. Bj Robert Shelford, M.A., F.Z.S. 



[Received October 7, 1911 : Read February 20, 1912.] 

 (Plate XLVIII.* and Text-figures 42-46.) 



Speaking in general terms the Blattidse may be regarded as a 

 somewhat defenceless group of insects, preyed upon by numerous 

 enemies both vertebrate and invertebrate, to escape which they 

 must rely on their skulking, cryptic habits, and on a high degree 

 of speed when disturbed. In accordance with their ciyptic mode 

 of life most cockroaches are obscurely coloured, harmonising 

 more or less perfectly with their inanimate surroundings, or, at 

 any rate, displaying no conspicuous markings to attract the 

 attention of potential foes. 



Exceptions to this cryptically coloui-ed type of cockroach, how- 

 ever, exist in some numbers and are dealt with in the following 

 pages. 



The Australian continent is the headquarters of a group of 

 Blattidae which presents all the features customarily associated 

 with extreme unpalatability. This group is the Pohjzosteria 

 section of the sub-family Blattinaj. Nearly all the species are 

 apterous and expose themselves freely, and many are endowed with 

 a most repulsive odour. Mr. W. W. Froggatt informs me that 

 Folyzosteria Imibata Biirm., P. cuprea Sauss., and others of this 



"* For exi)lanatiou of the Plate see p. 376. 



