290 W. F. R. WELDON. 



It appears, from the foregoing statements, that the nephro- 

 peritoneal sacs of the Decapoda should be regarded rather as 

 enlarged portions of a tubular system, such as that found in 

 Mysis and in the Thalassinidse, than as persistent rem- 

 nants of a '' coelomic " body-cavity, into which tubular 

 nephridia open. 



The presence of coxal glands in Nebalia,^ and of tubular 

 nephridia in the zocea of Eriphya,^ gives much interest to the 

 search for an embryonic coelom in these animals, which may 

 be expected to behave like the coelom of Peripatus. 



EXPLANATION OF PLATES XXI & XXII, 



Illustrating Professor W. F. R. Weldon's paper on " The 

 Renal Organs of Certain Decapod Crustacea." 



List of Reference Letters. 



Bl. Bladder. Br. Brain. B. ». Blood-vessel (or lacuna). Comm, Circum- 

 cesopLageal nerve-commissure. ^. 5. End-sac. Z^r. Labrum. iV. /j. Nephro- 

 peritoneal sac. CEs. (Esophagus. St. Stomach. Tu. Tubular portion of 

 " green gland." U. Ureter. 



Fig. 1, — Transverse section through the head of a Palaemon serratus, 

 showing the connection between the dorsal nephro-peritoneal sac and the 

 bladder. 



Fig. 2. — Transverse section through the same specimen, rather behind Fig. 

 1, showing the dilated median ventral portion of the neprho-peritoneal 

 system lying in the upper lip, and the dorsal portion lying above the stomach. 



Fig. 3. — Transverse section through the head of Fan dal us brevirostris, 

 just in front of the oesophagus, showing the ventral mesentery formed by the 

 two nephro-peritoneal sacs. 



Fig. 4. — Horizontal section through the bladder and end-sac of an adult 

 Virbius. The dotted lines indicate the course of the single renal tubule. 



' Claus, * Arb. Zool. Inst. Wien,' Bd. viii, Heft 1, 1888. 

 =» Ebedinski, 'Biol. Centralbl.,' x, p. 178. 



