133 



for food. On the other hand, many of the inhabitants of decayed logs, 

 as snails and slugs, use the log as a retreat and sally forth at night and 

 during moist weather to devour vegetation. Rotten wood also con- 

 tains many fungi affording fresh, living plant tissue. 



Representative animals of the forest litter, especially of its humus 

 layer, appear to be certain millipeds, as Callipus and Cleidogona. Cook 

 ('i lb, p. 451 ) has said of them : "Nearly all the members of the group 

 have essentially the same habits and live in clearly similar environ- 

 ments. They pass their lives buried in the humus layer of the soil or 

 among the dead leaves or other decaying vegetable matter that fur- 

 nishes them food." Elsewhere he says ('iic, p. 625) : "In nature at 

 large the millipeds have a share in the beneficial work of reducing dead 

 plant material to humus. Prussic acid and other corrosive secretions 

 may aid in the precipitation of colloidal substances in the humus, in 

 addition to the protection that they give by rendering the millipeds dis- 

 tasteful to birds and other animals that otherwise might feed upon 

 them. The precipitation of colloids enables the millipeds to keep their 

 bodies clean and protects them against the clogging of their spiracles." 

 Diem ('03, pp. 383-386) gives a good summary of the habitats and 

 foods of certain European diplopods. I am inclined to consider the 

 layer of litter as the habitat of the immature panorpid Bittacus, of 

 which three species were found in the Bates woods. The adults fly 

 about among the low vegetation much after the manner of the Tipuli- 

 dcs, with which they are easily confused when on the wing. It is prob- 

 able that the larva of Panorpa confusa West, has habits similar to 

 those of Bittacus. I have taken the adult of this species but once — at 

 Bloomington, Illinois, August 23, 1892, in dense damp woods. The 

 larvae of Panorpa are predaceous, and this is probably true of Bit- 

 tacus. The ant Stigmatomma pallipes is another representative of 

 this community (cf. Wheeler, '05, p. 373), as are probably also a 

 number of tipulid larvae. 



The animals of the humus layer appear to live much more active 

 lives than those deeper in the soil. This activity in itself allows them 

 a chance to secure the necessary supply of oxygen, which tends to be 

 deficient among the decaying vegetation; at the same time, moreover, 

 their movements must aid in the ventilation of the soil. It is of inter- 

 est to observe that millipeds abound in a habitat relatively deficient in 

 oxygen, abounding in carbonic acid, and are producers of prussic acid 

 (HCN), whose physiologic effect is to inhibit oxidation and nutrition. 

 Roth (Diem, '03, p. 385) submerged some diplopods in water from six 

 to eight hours and they survived. (For the marked resistance of ge- 

 ophiloids, see Ent. News, 24:121.) In nature they must often 

 meet with such conditions in the soil. One of the most abundant kinds 



