CIRREPEDIA. 



427 



link these genera even more closely together. In them, as in Alci/i/i* 

 there is no appearance of the segmentation of the anterior part of the 

 body indicated in Cryptophialus. If we disregard this apparent segmen- 

 tation, the four genera fall into a natural group for which the name 

 Abdominalia becomes misleading and for which Gruvel has proposed the 

 name Acrothoracica, in allusion to the fact that the terminal feet are 

 confined to more or fewer of the apical (terminal) segments of the 

 thorax. 



The group so formed has affinities, as pointed out by Darwin in the 

 case of Alcippe, with the Lepadidae. There are however indications that 

 they belong to a more generalized type than any of the Thoracica. If we 

 take the oral end of the disc of attachment as representing the region 

 of the 1st antennary segment, there is no such wide separation of the 

 mouth from this region as occurs in that group. Hence the relations of 

 the parts of the 

 adult body are 

 more nearly those 

 which obtain in 

 other groups of 

 Crustacea. Associ- 

 ated with the same 

 condition is the fact 

 that the fold (Fig. 

 271 x ) between the 

 mantle and the 

 dorsal body wall is 

 not extended into 

 the cephalic region, 

 dividing it into an 

 oral and preoral 

 part, as occurs in 

 the metamorphosis 

 of the Cirripedia 

 Genuina. The pres- 

 ence of an articu- 

 lated caudal fork 

 in Lithoglyptes and 

 Ko chlorine is a 

 generalized feature 

 which they share 

 with Lithotrya, Ibla and Alepas among the Pedunculata. Berndt * has 

 recently brought evidence to show that the appendages which have 

 been regarded as the caudal fork in Alcippe are the 6th pair of thoracic 

 appendages. 



Fam. 1. Alcippidae. The females (Fig. 275 &) live in hollows in the 

 columella of the shells of Fusi(s and Buccinuni (British) to the wall of 

 which they are attached by a large horny disc, the plane of which is 

 parallel with that of the orifice of the burrow. Their position in relation 

 to the surface of attachment is the same as that of the pupa of Lepas 

 (cf. Figs. 270 and 275). First pair of thoracic appendages large and 

 palpiform, and the three posterior appendages uniramous. They probably 



a 



FlG/275. Alcippe lampas (after Ch. Darwin), a. male.'very strongly 

 magnified ; 6, longitudinal section through female. A' the right 

 antenna (the left is seen through the transparent body) ; Cf 

 three posterior pairs of appendages ; D lobe of the mantle ; F 

 maxilliped (first thoracic appendage) ; eye ; Ov ovary ; P penis, 

 projecting from the orifice of the flask-shaped mantle cavity, at 

 the lower (anterior) end of which is situat?d T the testis ; 

 Vs seminal vesicle. The thickened band to the left of Ov 

 is the section of the large disc by which Alcippe is attached 

 to the wall of its burrow. 



* Zeits. fur wiss. Zool., Bd. 74, p. 396. 



