130 REPORT — 1860. 



On the Structure of the Lcpadidas. Bij R. Garner, F.L.S. 



In this paper the author bore testimony to the high regard for truth with which 

 Mr. Darwiu has recorded his labours, in respect to these animals, though further 

 observation has modified some of his conclusions, and indeed is still wanted. 



From finding fragments of shells, small pebbles, &c. in the cesopbagus of the 

 Lepas anatifera, the. author supposes that this part acts as a gizzard, comminuting 

 the food. With Poli he believes in the existence of a heart, situated on the back, 

 a little posterior to the base of the second pair of cirri : however, these observers 

 stand alone with respect to this point. The heart can only be seen in some speci- 

 mens, according to the state of the tissues, which vary much. It receives its 

 supply at the sides, and gives off vessels before and behind : other large and lon- 

 gitudinal vessels exist. 



With respect to the canal running along the abdominal side of the peduncle, 

 and communicating with the body of the animal, on each side, behind the adductor 

 muscle, the author thinks that by meaus of it the cavity of the prosoma is distended 

 with fluid, thus acting as an antagonist to the adductor, parting a little the shelly 

 valves. The communicating opening lies between the nerves and oviducts as they 

 course between the peduncle and the body. 



Mr. Darwin thought that these oviducts conveyed the ova from his ovaries, or 

 the salivary glands of Cuvier, into the peduncle, where ova are found sure enough. 

 But in some specimens, where they are distended with ova, the oviducts are easily 

 traced from the peduncle down into the body of the animal, making a sweep, and 

 apparently ending at the cavities and apertures called acoustic by Mr. Darwin, who 

 informs us that Krohn has also made out this point. The little membranous, 

 buskin-shaped follicle, found in this acoustic cavity, is sometimes wanting. 



Cuvier did not often use the microscope, or he would have soon discovered that 

 his so-called ovaries are, in reality, testes. 



Little need be said, after Mr. Darwin, respecting the nervous system. The sub- 

 oral ganglion, besides being connected by a ring with the supra-oral ganglia, supplies 

 the salivary glands, the adductor muscle, the viscera, and the mantle by means of a 

 large anterior branch : also it gives others to the mouth and first cirri, and is con- 

 nected of course with the chain of ganglia between the other cirri. From the 

 supra-oral pair of ganglia, which are in close apposition, two large nerves (anten- 

 nary of Mr. D. ) go to the peduncle, and two minute twigs to the eye, described 

 exactly in the " Lepadidse. With respect to this eye Mr. Darwin observes, " in all 

 the genera the double eye is seated deep within the body ; it is attached by fibrous 

 tissue to the radiating muscles of the lowest part of the cesopbagus, and lies actually 

 on the upper part of the stomach ; consequently a ray of light, to reach the eye, has 

 to pass through the exterior membrane and underlying corium connecting the two 

 scuta, and to penetrate deeply into the body." This is not quite all ; the little 

 organ is made perfect in its adaptation, by a small oval or lozenge-shaped trans- 

 parent spot in these coverings to admit the light, and exactly behind this spot the 

 eyelet may always be easily seen or found. In specimens of Gonchoderma Hunteri, 

 parasitic on the carapax of a crab from Amoy, this visual organ is situated between 

 the mouth and the adductor. 



The so-called proboscis appears to act as an ovipositor, and probably in the pre- 

 hension of the food. The ova are finally attached to the " ovigerous fraena " as 

 broad sheets, with the assistance of a cement, which sometimes glues them unna- 

 turally together. The fatty matter with which the mantle abounds appears to go 

 to their nutrition, and is apparently taken in at the roots of the frsena. In this 

 mantle, in some species, the young animals are imbedded, and within its cavity 

 impregnation takes place. 



The author's specimens of Lepas came on shore last January at Ivimmeridge, 

 attached in vast quantities to a beam of pine. Some were a foot and a half in 

 length ; mostly simple, but others springing one from another. They are tenacious 

 of life, and appear to be generally cast on shore upon our coasts in rough winter 

 weather. The author has had large living JBalani picked up in the Mersey, and 

 has Lepadidse attached to nuts of China, the small shells of a Sepia, and minute 

 ones on the shells of Ianthina and Spirilla from the Gulf-weed. 



