ins 



CIRRIPEDIA. 



1118 



the rudimentary rostrum ; upper latent irregularly oval The com- 

 ]>l<-meutal male flask-formed, with four rudimentary valve*. 



It u a native of the sea* of Great Britain, Ireland, France, Norway,, 

 and Naples. Found attached to horny coralline*, according to Forbes 

 and MacAndrvw, at from twenty to thirty, sometimes even to fifty 

 fathonu in depth. There are five other species of this genus. They 

 are all characterised by the presence of the complements! male. 



Pollicipet, Leach (Lepai, Linnams ; Anal if a, Bruguicres; Mit<lla, 

 Oken ; Jtampkidimia, Schumacher ; Polyltpa*, De Blainvillo ; 

 l'<i)'i!ntuui, J. K. Qray). Valves from 18 to above 100 in number; 

 Utcra of the lower whorl numerous, with their lined of growth 

 directed downward* ; subrostrum always present; peduncle squami- 



! : 



f. milella, Sowerby. It is Lepai mitella, Linnteus ; Polylepat 

 mitella, De Blain. ; CapittUiun mitella, 

 Qray. Capitulum with only one whorl 

 of valves under the rostrum ; the 

 upper pair of latera viewed internally 

 are three or four times as large as 

 the lower lutera, which overlap each 

 ot her laterally ; scales of the peduncle 

 symmetrically arranged in close 



This species is found in the seas of 

 the Philippine Archipelago and the 

 Chinese Sea. There are five other 

 species. They are found attached to 



p^lici botn nxed and floatm 8 objects in the 



warmer, temperate, and tropical seas. 



Lithotrya, G. B. Sowerby (LMolepat, De Blainville ; Abtia, Leach ; 

 Srimaui and Conduit rya, 3. E. Gray ; Lepcu, Gmelin ; Anal if a, Quoy 

 and Gaiuiard). Valves 8, including a small often rudimentary ros- 

 trum and a pair of small latera ; lines of growth finely crenated ; 

 peduncle covered with small calcareous scales ; those of the upper 

 whorls crenated ; attached either to a basal calcareous cup or to a 

 row of discs. 



Mr. G. B. Sowerby, who instituted the genus, considers it as inter- 

 mediate between the Sessile nd Pedunculated Cirripedes ; and states 

 that it possesses a peculiarity not to be found in any hitherto 

 described genus of this class, namely, that of penetrating stones for 

 its habitation. Rang says that De Blainville is of opinion that the 

 genus is only a true Anatifa, which had affixed itself upon the valve 

 of a Venerupit at the bottom of one of the cavities which that bivalve 

 hollows out for itself. De Blainville, in his ' Malacologie,' describes 

 it under the name of Lithulepai, sinking Sowerby's name altogether, 

 though he says the genus was newly established by him, quotes his 

 description, and merely states that he has never seen the Cirripede. 



As the means by which many of the ifollutca bore into the rocks 

 in which they reside are at present unknown and are matters of much 

 discussion, the conclusions at which Mr. Darwin has arrived with 

 regard to the species of Lithotrya are of high interest. After 

 describing accurately the structure of the valves, the peduncle, the 

 muscles of the peduncle, the basal calcareous cups or discs, and the 

 internal structure of the cup, he concludes : " The several species 

 occur imbedded in soft calcareous rocks, in massive corals, and in 

 the shells of Mulluica and of Cirripedes. It has been doubted by 

 several naturalists whether the basal calcareous cup at all belongs to 

 the Lithotrya ; but after the foregoing microscopical observations on 

 it* structure it is useless to discuss this point. So again it has been 

 doubted whether 'the cavity is formed by the cirripede itself ; but 

 there is so obvious a relation between the diameters of specimens of 

 various sizes and the holes occupied by them that I can entertain no 

 doubt on this head. The holes moreover are not quite cylindrical, 

 but broadly oval, like the section of the animal The simple fact 

 that in this genus alone each fresh shelly layer round the bases of 

 the valve*, and therefore at the widest part of the capitulum, is 

 sharply toothed ; and secondly, that in this genus alone a succession 

 of sharply-serrated scales, on the upper and widest part of the 

 peduncle, is periodically formed at each exuviation, and that con- 

 sequently the teeth on the valves and scales are sharp and fit for 

 wearing soft stone at that very period when the animal has to increase 

 in size, would alone render the view probable that the Lithotrya makes 

 or at least enlarges the cavities in which it is imbedded. Although 

 it may be admitted that LMotrya has the power of enlarging its 

 cavity, how does it first bore down into the rock? It is quite certain 

 that the basal cup is absolutely fixed, and that neither in form nor 

 state of surface it is at all fit for boring. I was quite unable to 

 answer the foregoing question until seeing the admirable figures by 

 Reinhardt of L. Nicooarita still attached in its cavity. Subsequently 

 I obtained from Mr. Stutchbury several pieces of rock completely 

 drilled with holes, many of small diameter, by L. dorialit ; and in 

 these I found numerous instances of the linear rows of little discs 

 like those of L. fficobarica, showing in the plainest manner that each 

 time a? new disc is formed, that is, at each exuviation, the animal 

 moves a short step downwards ; and as the lowest of these little discs 

 in none of the burrows was placed at the very bottom, we see that 

 the lowest point of the peduncle must be the wearing agent. In the 

 peduncle of an individual of L. dorialit, nearly ready to moult, I 



found, it may be remembered, beneath and round the basal disc, 

 under the old membrane of the peduncle, a new membrane studded 

 with calcified beads, but with the horny star-beaded spines not yet 

 developed ; whilst on the old outer coat these latter had been worn 

 down quite smooth, and the calcified beads worn entirely away. Here 

 then we have an excellent rasping surface. With respect to the power 

 of movement necessary for toe boring action, the peduncle is amply 

 furnished with transverse, oblique, and longitudinal Htrueless muscles, 

 the latter attached to the basal disc. In all the Pedunculate I have 

 reason to believe that these muscles are in constant slight involuntary 

 action. This being the case, I conceive that the small blunt spur- 

 like portion of the peduncle descending beneath the basal rim of the 

 lowest disc would inevitably partake slightly of the movements of 

 the whole distended animal As soon as the Lithotrya has reached 

 that depth which its instincts point out as most suitable to its habits, 

 the discs are converted into an irregularly growing cup, and the 

 animal then only increases in diameter, enlarging its cavity by the 

 action of the serrated scales on the peduncle, and of the serrated 

 lower edges of the valves of the capituluni. With respect to those 

 reversed individuals attached with their capitulums downwards, I 

 suppose that the larvu.* had crept into some deep cavity perhaps made 

 originally by a Lithotrya, of which the rock in the specimen in question 

 was quite full, and had there attached themselves. Finally, it appears 

 that in Lithotrya the burrowing is simply a mechanical action : it is 

 effected by each layer of shell in the basal attached discs overlapping 

 in a straight line the last-formed layer ; by the membrane of the 

 peduncle and the valves of the capitulum having excellent and often 

 renewed rasping surfaces ; and lastly, by the end of the peduncle (that 

 is, homologically the front of the head) thus roughened, extended 

 beyond the surface of attachment, and possessing the power of slight 

 movement." 



L. dortalu, G. B. Sowerby. It is the LC/KU donalit, Ellis ; Lit/to- 

 lepai de Mont Serrat, Do Blainville. Scuta narrowly overlapping the 

 tergu ; carina internally concave ; rostrum 

 as wide as two or three of the subjacent 

 scales ; latera with their internal sur- 

 faces narrowly elliptical, as long as five 

 of the subjacent scales ; upper scales of 

 the peduncle less than twice as large as 

 those in the second whorl. 



This species is found imbedded in lime- 

 stone at Barbadoes, Venezuela, and the 

 Honduras. 



L. cauta, Darwin, named from a unique 

 specimen, was found imbedded in u t'onia 

 or Tetraclita from New South Wales. 



/.. .\icobariea, Reinhardt, is a rape spe- 

 cies occurring in the Nicobar Islands. 



L. Rhodiopm, Darwin, is named from a 

 Litttutrya dorialit, specimen imbedded in a massive coral in 



the British Museum. 



L. truncata, Darwin, found imbedded in coral rock in the Friendly 

 Islands and Philippine Archipelago. 



L. Valentino,, Darwin, from two specimens imbedded in an oyster- 

 shell, in the British Museum, from the Red Sea. 



t Order II. Abdomtnalia. 



Cirripedia having a flask-shaped carapace. Body consisting of 1 

 cephalic, 7 thoracic, and 3 abdominal segments, the latter bearing 3 

 pairs of cirri ; the thoracic segments without members ; mouth with 

 the labrum greatly produced, and capable of independent movements ; 

 oesophagus armed with teeth at its lower end ; larva firstly egg-like, 

 without external limbs or an eye ; lastly, binocular, without thoracic 

 legs. 



This order contains only one genus and one species, Cryptoph ialut 

 minutui, Darwin, 1854. It is very distinct from all other Cirripedes, 

 but more nearly allied to Alcippc amongst the Lepadidie than to any 

 other form. It bores cavities in the Concholepai Peruviana, and is 

 of very minute sue. 



Order III. Apoda. 



Cirripedia, with the carapace reduced to 2 threads, serving for 

 attachment. Body consisting of 1 cephalic, 7 thoracic, and 3 

 abdominal segments, all destitute of cirri ; mouth suctorial, with the 

 mandibles and maxilla:, placed back to back, inclosed in a hood, 

 formed by the union of the labrum and palpi; metamorphoses 

 unknown. 



This order, like the last, contains only one genus and species, Proteo- 

 Itpai birincta, Darwin, 1854. It was found parasitic within the sac 

 of another Cirripede in the West Indies. Until most closely examined 

 the Proteolepai would never have been imagined to have belonged to 

 the class of Cirripedia. In external appearance it resembles the larva 

 or maggot of a fly ; its mouth is unlike that of sny known type in the 

 articulate kingdom. 



Fottil Cirripedia. 



As with the recent BO with the fossil species of this family, we are 

 most indebted for our knowledge of them to the exhaustive labours 

 of Mr. Darwin, whose recent investigations on this subject have 



