XI 



PHYLUM ARTHROPODA 



611 



lficr.2 



Ihcr 3 



into a chain by a series of double connectives ; the last pair of 



abdominal ganglia, situated in the sixth segment of the abdomen 



(abdO), are larger than the others, and 



supply the segments behind. A visceral 



nervous system, ramifying on the 



anterior part of the alimentary canal, 



is connected with the two cesophageal 



connectives by two nerves, which join 



above the oesophagus to form a median 



frontal ganglion. 



The organs of special sense are 

 the eyes, the antennae, and the palpi. 

 The eyes are compound each being 

 made up of a large number of simple 

 elements similar to those that go to 

 make up the eye of Apus (see p. 523). 

 The antennae and palpi, together with 

 the anal cerci, act as organs of touch. 

 In addition, certain setae on the 

 antennae appear to have an olfactory 

 function. 



Reproductive organs. In the 

 male the testes (Fig. 507, test.) are a 

 pair of small bodies which lie in the 

 fourth and fifth segments of the 

 abdomen immediately below the terga. 

 From these a pair of delicate tubes, the 

 vasa deferentia, lead to the vesiculce 

 seminales, two tufts of whitish caeca, 

 which together constitute what is 

 known as the " mushroom-shaped gland " ; these open into the 

 anterior end of the ejaculatory duct (duct, ej.), an unpaired tube 



506. Cockroach. General 

 view of the nervous system. aM6, 

 sixth abdominal ganglion ; ant. an- 

 tennary nerve ; br. brain ; conn. 

 cesophageal connective ; inf. sub- 

 cesophageal ganglion ; opt . optic 

 nerve ; thor.l, thor.2, thor.3, first, 

 second, and third -thoracic ganglia. 

 (After Miall and Denny.) 



FIG. 507. Cockroach. Male 

 reproductive organs, lateral 

 view. duct. ej. ductus ejacula- 

 torius with mushroom-shaped 

 gland ; stern. 7, sternum of 

 seventh segment of abdomen ; 

 terg. 7, tergum of the same 

 segment ; test, testis. (After 

 Miall and Denny.) 



ill.gld 



FIG. 508. Cockroach. Female 

 reproductive organs, coll. gld. col- 

 leterial glands ; od. oviducts ; ov. 

 ovaries. (After Miall and Denny.) 



