IV 



PHYLUM CCELENTERAJA 



179 



Order 2. — Coronata. 



This group includes a number of rare and beautiful Medussi of curiously 

 complex structure, of which Pericolpa may be taken as aw^ example. The 

 umbrella (Fig. 132) is usually conical, and is divided by a horizontal furrow 

 [coronary groove.) into an apical region or cone (en.) and a marginal region or 



circ. a 



mnb 



Fin. 132. Pericolpa quadrigata. A, external view; B, vertical section, circ. s. circular 

 sinus ; en. cone; jr. f. gastric filaments; ffom. gonads; tng. Ip. marginal lappets; mnb. manu- 

 brium ; mth. mouth ; ptl. I. pedal lobes ; st. stomach ; t. tentacles ; tc. tentaculocysts ; tn. 

 t.i-nioles. (After Haeckel.) 



crown; the crown is again divided by a second, rather irregular horizontal 

 furrow into a series of pedal lobes (pel. I. ), adjacent to the cone, and a series of 

 marginal lappets (nig. Ip.), forming the free edge of the bell. In some of the 

 Coronata, such as Pericolpa, the pedal lobes and marginal lappets correspond 

 (i.e. are in the same radii) ; in others (Periphylla, Ephyropsis) they alternate. 



N 2 



