LIFE-HISTORY AND PHYSIOLOGY. 5 



A wonderful diversity of pattern and structure occurs in the tunics of the several 

 species of the genus, often exhibiting characters so well marked that a mere frag- 

 ment is sufficient for the determination of a species; and all are constructed on a plan 

 related to the annual replacement and expansion of the corm. 



The tunics of the great majority of species consist of a fibrous skeleton on a 

 membranous base; presenting great variety of pattern, and every gradation between 

 parallel unbranched fibres, and reticulated fibres. 



In some species the tunics are composed almost exclusively of thin membrane; 

 and in others, again, the tunics as in C. Icevigatus, (Fig. 5, FJ and in the annulate 

 species are strongly coriaceous throughout, without any distinct fibrous structure. 



The coriaceous and membranous tunics occasionally present a fibroid structure 

 without having true fibres; and, as in the case of C. aureus, (Plate LV. fig. 12, e,J 

 and its allies the coriaceous membrane is more or less split up into flat fibre-like 

 parallel divisions. The most remarkable tunic structure is present in two eastern 

 species, C. Fleischeri, (Plate LXVI, and Fig. 4, FJ and C. parviprus, (Plate LXVII,) 

 in which the fibres are distinctly platted into parallel vertical strands, a structure 

 which also occurs in some eastern species of Xiphium. 



Fig. -1. 



Fig. 4. A. The main tunic of C. Sieberi; B, of C. sativus, var. Pallasii; < '. of C. serotinus; 

 J), of C. carpetanus; E. of C. versicolor; F. of C. Fleischeri. 



The basal tunic also presents a great variety of structure. It generally consists 

 of star-like bodies composed of fibrous rays spreading from a central disc (Fig. 5, b,); 

 and in all the species with coriaceous tunics, excepting C. Icevigatus, the basal tunic 



