444 BALANIDiE. 



Cirri. — The cirri are short, particularly the three anterior pairs. 

 The segments in all are singular, from being so much compressed, so 

 short, and of such great breadth ; they are protuberant in front. In 

 the second and third cirri, the broad lateral faces of the segments, 

 with the exception of the posterior face of the posterior ramus, are 

 almost bare of spines. In the three posterior pairs of cirri (PI. 29, 

 fig. 6), the segments are protuberant in front, and support three pairs 

 of short thick spines, with an intermediate tuft ; the dorsal tufts are 

 unusually small : their pedicels are remarkable from the upper seg- 

 ment, and the upper part of the lower segment, being produced into 

 a rounded protuberance, dotted with spines : I have met with a similar 

 structure only in Scalpellum vulgare. In the third pair (fig. 5) there 

 is only a trace of this structure ; and in the second pair the anterior 

 margin of the pedicel is straight, and clothed with three tufts of bristles. 

 The pedicel of the first cirrus is very broad, and clasps the mouth. 



The cirri and mouth are dark chocolate red, like the outside of the 

 animal and the upper part of the sack. The thorax is redder and 

 paler. The four posterior articulations of the thorax are straight and 

 transverse; the next segment, or that corresponding with the second 

 pair of cirri, is slightly inflected, in the usual way, towards the pro- 

 soma. The prosoma is pale coloured, extraordinarily elongated, and 

 bluntly pointed ; it extends down (see the dotted outline in PI. 17, 

 fig. 4 a) about one third of the length of the whole animal. The 

 orifice leading into the acoustic sack forms a freely depending little 

 point beneath the basal articulation of the first cirrus. The stomach 

 in the uppermost part is deeply and closely plaited longitudinally, 

 but has no caeca; it runs down (externally coated, as usual, by the 

 testes) to the lower point of the prosoma, and is then doubled back 

 on itself, so that it is very long. 



Generative System. — The probosciformed penis is short and thick, 

 and covered with verv minute tufts of bristles : there is no knife-edged 

 projection at its dorsal base. The vesiculae seminales are much con- 

 voluted and of great length. The ovarian tubes form a small sheet 

 within the rudimentary shell, in the normal position, over the basal 

 membrane ; and likewise higher up between the two folds of corium 

 surrounding the pseudo-peduncle ; they do not, however, appear to 

 occur round the lower part of the peduncle : they extend highest on 

 the rostral and carinal sides, and lowest on the two lateral faces. The 

 ova are wonderfully numerous ; they are -^^ths of an inch in length : 

 they form, instead of two thin lamellae, two almost cylindrical packets, 

 which are held together by most feeble membrane. Each packet, in 

 the upper part lies between the two folds of the branchiae ; and in the 

 lower part, is embraced only by the larger outer fold. The two packets 

 of eggs sometimes cohere together at their lower ends. 



Imbedment . — The shell is imbedded up to its summit, but the shell 

 is very shallow. The imbedment seems due either to the compression 

 of the epidermis of the porpoise, or to its formation beneath the shell 

 having been checked ; the outline of the true skin under the dark-coloured 

 epidermis is not in the least aifected. The epidermis fills up the bay-like 

 spaces formed by the inwardly folded walls, and firmly adheres to them. 



