158 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3 d Ser. 



5.5 mm; length of caruncle, 2.5 mm. Length of largest specimen, 26 mm.; 

 greatest breadth of same, 5.5 mm. 



This species is common at San Pedro, from low-water 

 mark to three or four fathoms, and probably to greater 

 depths. It frequents shelly and stony bottoms. The enor- 

 mous, matted rootstocks of the bladder kelp (Mac?'ocystis 

 fyrifera~) afford it a welcome shelter. Many specimens 

 were obtained from these rootstocks in July, 1895, when 

 they washed ashore from San Pedro Bay, where the kelp 

 grows to a depth of eight or nine fathoms. 



The number of somites is variable, ranging, among 

 twelve specimens, from 30 to 37 1 . The largest, measuring 

 26 mm. in length, had the largest number of somites, and 

 the smallest, 16 mm. in length, had the least; but an in- 

 crease in the number of somites as the size increases is by 

 no means the rule. 



All my specimens (with the exception of a single one 

 dredged near Monterey from 12 fathoms) were obtained at 

 San Pedro in July and August, 1895. None were taken 

 there in December, 1895, although the same ground was 

 dredged carefully. The larger individuals were sexually 

 mature in July. 



E. aurantiaca is most nearly allied to E . myrtosa Savigny, 

 and to E. meditcrranea Grube. It agrees with these in hav- 

 ing: (1) seven pairs of gill-trunks, which are not extensively 

 branched and have no erid buds; (2) the caruncle extend- 

 ing to the fifth somite ; (3) the number of segments. It dif- 

 fers in having: (1) setee of two kinds; (2) the latoral-dorsal 

 cirrus between the third and fourth gill-trunks, instead of 

 between the second and third. 



1 The number of somites ran as follows: 



37 somites 2 specimens 



36 " t 



35 " 1 



34 " 3 



33 " I 



32 " 2 " 



31 " I 



3° " I " 



Average, 33^. 



