280 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



excellent characters. Thus we have the multitude of pustular 

 or stromatlc species, which grow on the branches of trees, or 

 on decayed wood ; while the more elongated clavate or simply 

 globose forms yield the species of Hypoxylon and Cordyceps 

 (Fig. 17, h). Some of the most beautiful and remarkable are 

 those which grow on insects. Cordyceps Rohertsii, which 

 grows upon the larvae of Hepialus virescens, is well known to 

 every one who has seen or received specimens of the produc- 

 tions of New Zealand. But this is far exceeded in size by a 

 species which grows on an enormous larva or the banks of the 

 Murrambidgee, of which, at present, immature specimens only 

 have been examined. Most of the larvae which produce insects 

 probably carried the seeds of the disease with them into their 

 subterraneous retreat; and in one species, at least, which affects 

 wasps, the clubs with their curled stems are carried about till 

 the unhappy insect sinks under the exhaustion produced by 

 the waste of its fatty tissue. 



2S6. As regards their geographical distribution, it may be 

 asserted that Sphcerice are to be found in almost every part of 

 the world. When the air has the proper degree of moisture, 

 they are most abundant in temperate climates, but they are by 

 no means wanting in the tropics, especially such forms as ap- 

 proximate to Xylaria hypoxylon, which is one of the most 

 cosmopolitan of plants. The finest forms, indeed, are found in 

 the warmer countries. In New Zealand, species resembling 

 those of the northern hemisphere are not uncommon, and we 

 have a few species from most hot countries. In some, as in 

 Cayenne, they are exceedingly abundant, the forms being fre- 

 quently peculiar ; while some of the species are so singular 

 that at first sight they would scarcely be recognised as Fungi, 

 resembling far more a sort of black caddis case which was once 

 described as a Dentalium, and figured as a doubtful species by 

 Sowerby in the Genera of shells under Dentalium (Fig. 9). But 

 even in temperate climes they are not always very prevalent. 

 Amongst the Sikkim Himalayas, for instance, very few species 

 were collected by Dr. Hooker, though his attention was turned 

 to every part of the vegetable world, and many species of far 

 greater obscurity are comprised in his collections. Such com- 



