REPORT ON THE DEEP-SEA MEDUSAE. 79 



peripheric coronal intestine is only connected openly with the axial principal intestine 

 at four points, viz., at the four perradial gastral openings (go). 



The remarkable, enormously large circular sinus, or coronal sinus (" sinus coronaris," 

 or " canalis coronaris,") cs ; PI. XX. fig. 8, cs ; PI. XXI. figs. 12-18, cs) is that part 

 of the gastro vascular system which specially distinguishes the Peroniedusee from all 

 other Medusae, and which does not recur in the same form and to the same extent in 

 any other group of Medusas. It forms a colossal annular pouch which is placed more or 

 less subvertically, and in Pervphylla mirabilis is 30 mm. high, so that it fills the half 

 of the whole height of the umbrella. In the circular sinus we distinguish an upper or 

 proximal and a lower or distal margin, and an inner or axial and an outer or abaxial 

 wall. The upper margin and the outer wall of the circular sinus are without any 

 opening ; on the other hand, it communicates at the lower margin by sixteen horizontal 

 clefts, with the sixteen coronal pouches, and at the inner wall by the four vertical gastral 

 openings with the central stomach. The lower or distal margin (fig. 15, cs) coincides 

 with the proximal margin of the coronal muscle (mc), and has, consequently, sixteen sub- 

 radial projecting corners (PI. XIX. fig. 6). The aboral or proximal margin (fig. 15, cs), 

 is a simple circular ring of the subumbrella, which coincides with the plane of the 

 pylorus ; the hollow space of the coronal sinus is here completely closed, and does not 

 communicate with the surrounding circular pylorus ; the proximal margin of the circular 

 sinus (fig. 15, cs) is completely separated from the pyloric opening (gy) by the four 

 interradial funnel cavities (ii) (which touch here), and only touches the pyloric opening 

 externally in the four perradial pyloric corners (gyl). The external, umbral, or abaxial 

 wall is formed by the smooth concave inner surface of the gelatinous umbrella, and is 

 covered by dark pigment, which is deposited in the form of black-brown balls in the 

 endoderm cells of the umbral wall. The inner, subumbral or axial wall of the circular 

 sinus is formed by the subumbrella, which here assumes very compbcated conditions 

 in consequence of the strong development of the four funnel cavities. Considered more 

 closely, this axial wall is divided into an upper broader, and a lower narrower section, 

 which is bounded by the subumbral palatine ring or the insertion of the four perradial 

 palatine nodes (gh) at the subumbrella. The upper or proximal section of the axial 

 wall, above the palatine nodes, is pierced in its entire length by the four perradial gastral 

 openings, these important clefts already described, by which the hollow space of the 

 central stomach opens into the coronal sinus (go). The lower or distal section of the 

 axial wall, on the contrary, is perfectly simple, without openings ; the deltoid muscles 

 (md) lie on its subumbral surface. Moreover, the four pair of genitalia (fig. 20, sm) lie in 

 the four quadrants of the axial wall of the coronal sinus, which are separated by the four 

 gastral ostia, The colossal hollow space of the coronal sinus forms a powerful closed 

 pouch; apart from the four septal nodes which I shall next describe, it is perfectly simple, 

 and, moreover, so wide that I could easily introduce three of my fingers, and so realise 



