400 



IN VERTEBRATE MORPHOLOG 7. 



most part of the stalk are the two scuta (sc), while above 

 these are the terga (te), also paired, the opening into the in- 

 terior l}'ing between the terga and the scuta of opposite sides. 

 In Scalpellum between the two scuta a sixth, unpaired, piece, 

 the rostrum, is inserted, and in the same genus between the 

 scuta, terga, and cariua and the summit of the stalk small 

 accessory pieces occur; and if one imagines a disappearance 



T 



Cir 



Car 



B 



FIG. ISl.Lepasfascmilaris. A, exterior; B, structure. 

 ag = auteunary gland. Ov = ovary. 



Car = carina. pe = peduncle. 



Cir = cirrus Sc = scutum. 



M = shell-muscle. t = testis. 



Od = oviduct. Te = tergum, 



Vd vas deferens. 



of the stalk of such a form, an enlargement of these accessory 

 pieces, usually six in number, and their articulation to form 

 a wall-like circle around the body of the animal, the scuta 

 and terga closing it in and forming as it were a roof, an idea 

 of the arrangement of the shell of Bcdanus, the acorn-barnacle, 

 will be obtained. 



No special respiratory organs exist, the entire surface of 

 the body probably performing this function, nor does a heart 

 seem to occur in any member of the group. The nervous 



