1863.] MR. J. Y. JOHNSON ON A NEW SPONGE. 2.57 



from the posterior extremity of the plate. At this place there is a 

 small sharp tooth, aud here commences a low crest which crosses 

 the plate with a curve and divides it into two unequal portions. The 

 common basal joint of these plates has a small sharp tooth at its 

 postero-exterior angle. 



Large quantities of this PencBus are taken at the mouth of the 

 Tagus during the spring aud summer months ; and it frequently 

 appears on the breakfast-tables of the hotels in Lisbon, where indeed 

 it first attracted my attention. It is known in the market under the 

 name of " Camarao," i. e. Prawn. The living Crustacean has a pale 

 red colour, which deepens on being boiled into the pinky red of our 

 Prawn. It may be readily distinguished from Penceus caramote, 

 which has also been taken on the coast of Portugal, by the single 

 crest on the carapace, by the absence of teeth from the underside of 

 the rostrum, by the presence of a spine near the anterior lateral 

 angles of the carapace in addition to the spine between the bases of 

 the inferior antennae and the eye-stalks, by the much greater length 

 of the filaments of the superior antennae, which in P. caramote are 

 not more than a fourth of the length of the carapace minus the 

 rostrum, by the absence of spines from the two basal joints of the 

 second and third pairs of legs, and by the presence of a single spine, 

 in place of three, at each side of the caudal segment of the abdomen. 



Examples having a total length, including the rostrum, of 5| inches, 

 and a carapace with a width of rather more than half an inch, are not 

 uncommon ; but the finest specimen I have seen was kindly pre- 

 sented to me by Dr. J. V. Barbosa de Socage, Director of the Royal 

 Museum of Lisbon. This specimen, which is now in the British 

 Museum, has the following dimensions : — 



inches. 

 Total length from tip of rostrum to end of caudal 



6 

 Iff 



plates 6 



Rostrum, length l| 



Carapace, without rostrum, measured at the side, and 



including the frontal spine ] J-^ 



Carapace, width 1^ 



Abdomen, length to the tip of the caudal segment . . 3i| 



First legs, length 1 i 



Fifth legs, length 2-W 



Outer pedipalps, length 1 9 



7. Description of a New Siliceous Sponge from the Coast 

 OF Madeira. By James Yate Johnson, Corr. Mem. Z. S. 



Order SILICEA, Bowerbank. 

 Dactylocalyx, Bowerbank, Phil. Trans. 1862. 



Skeleton siliceo-fibrous. Fibres solid, cylindrical. Reticulations 

 unsymmetrieal. 



Proc. Zool. Soc— 18G3, No. XVII. 



