364 



Some were taken in the neighbourhood of Lord Howe's Island, 

 S. lat. 31 31", E. long. 159 5", some near Norfolk Island, S. lat. 

 29 2", E. long. 168 2", and others, although in smaller numbers, 

 in different parts of our track. They generally made their appear- 

 ance after dusk in the evening, and presented a great diversity in 

 size, form and other external characters, which is due to changes in 

 the muscular system, a variable amount of pigment spots, &c. In- 

 deed at first I fully believed that several distinct species had been 

 brought up together, but this idea was abandoned when I observed 

 the most dissimilar forms gradually assume so close a resemblance 

 to each other, as ultimately to render it difficult to distinguish them. 



From these facts I am much inclined to think that the three spe- 

 cies described by Quoy and Gaimard, viz. P. amboinensis. P. punc- 

 tulata and P. rubra, P. Lichtensteinii (Eurydice Lichtensteinii of 

 Eschscholtz) and P. rosea of D'Orbigny, are all referable to Peron's 

 original species P. bucephala. 



The body of Phyllirrhoe is elongated in form and compressed 

 laterally, presenting for description an anterior and posterior extre- 

 mity, a right and left surface, and a dorsal and ventral border. The 

 head is surmounted by two lengthy, somewhat flattened and acumi- 

 nate tentacula ; the eyes lie beneath the skin, not being visible ex- 

 ternally, and the mouth is in the form of a short truncated proboscis, 

 with a vertical opening. The oval-shaped body is on an average 

 about one inch and a half in length, which is something over twice 

 the measurement from the dorsal to the ventral border taken at the 

 middle or broadest part. The tail is quadrilateral in figure, gradu- 

 ally widening towards its posterior border, which is exceedingly 

 thin. The outer integument is perfectly transparent and lined by 

 muscular bundles, disposed longitudinally, and somewhat more than 

 their own breadth apart. These communicate with one another by 

 oblique branching slips, which thus form a kind of network enclosing 

 long lozenge- shaped spaces. Here and there nerve-trunks of con- 

 siderable size accompany the longitudinal bundles, dividing off into 

 smaller twigs, which distribute themselves at pretty equal distances 

 in a direction more or less perpendicular to that of the muscular 

 fibres. Scattered about at irregular intervals amongst these struc- 

 tures are numerous reddish-brown pigment-spots, in the centre of 

 each of which a clear vesicle is generally distinguishable. As above 



