THE SESSILE BARNACLES. 



17 



In all species examined the rami of cim iv, v, and vi are nearly 

 alike in length and armature. The segments in nearly every speci- 

 men examined have three pairs of spines on the anterior side, the 

 lower pair being very small, and usually there are two unequal spines 

 at the posterior distal angle of each segment. The chajtotaxy is so 

 similar that it is hardly necessary to figure cirri of the several species. 



Fig. 7.— Verruca alba, maxilla (a) and jiandible (6) of specimen figured in pl. 2, figs. 1-1b. 



The relative length and number of segments of the cirri are given 

 in the following table, in all cases from individuals believed to be 

 adult. It is, of course, understood that young barnacles have cirri 

 of fewer segments than old ones. 



Species. 



V.stromia. 



V.alba 



V. nrta 



V . floridana . 

 V . calolheca . 



V.c.flavidula 



V.c. heteropoma . 



V.entobapta 



V .xanthia 



V.ewjlypta 



V.darwtni 



V.rathbuniana. . 



V.hoeki 



V.bicornuta. 

 V.hatolheca. 



Cirrus i. 



Relative length 

 of anterior to 

 posterior ranii. 



Slightly ui 



equal. 

 One-third.. . 

 Subequal. . . 

 Three-fifths . 

 Two-thirds . 



Three- fourths. 



....do 



Two-thirds . . . 



Subequal 



Subequal 



Subequal 



Slightly un- 

 equal. 



Subequal 



Subequal 



Equal 



Ntunber 

 of seg- 

 ments of 

 both 

 rami. 



7,9 



10,21 

 11,12 

 11,14 

 10,12 



9,14 



12. 13 

 S,12 



12,12 



17,17 



8,8 



10,11 



10,12 

 10,11 



12. 14 



Cirrus ii. 



Relative length of 

 anterior to pos- 

 terior rami. 



<0ne-half. 



One-third 



Two-thirds 



Three-fourths 



Slightly une<iual . 



Three-fourths. 



do 



Subequal 



Three-fourths . 

 Three-fifths... 

 Two-thirds . . . 

 Four-fifths 



7,16 



9, 21; 8,18 

 10,15 



Slightly unequal. 



Three-fourlhs 



Three-fifths 



Number 

 of seg- 

 ment s of 

 both 

 rami. 



11,15 

 11,14 

 15,16 

 10, 15 

 9,18 



6,11 



15,15 

 7,13 

 9,22 



Cirrus iii. 



Relative length 

 of anterior to 

 posterior rami. 



< One-half. 



Three-fourths. 

 Subequal. 

 Subequal. 

 Slightly un- 

 equal. 

 Subequal. 

 Subequal. 



Subequal. 

 Subequal. 

 Subequal. 

 Subequal. ' 



Subequal. 

 Subequal. 

 Subequal. 



