lO PATTEN AND REDENBAUGH. [Vol. XVI. 



densed connective tissue neurally to the integument between 

 the fifth and sixth pairs of legs. A similar bundle unites it 

 with the integument just outside of the chilaria, and from 

 here on it is attached by a double base all along the integu- 

 ment of the abdomen, between the ventral longitudinal and 

 the " branchio-thoracic " muscles. It furnishes attachment for 

 all the veno-pericardiac muscles. 



Benham, in his paper " On the Muscular and Endoskeletal 

 Systems of Lhnuliis''' ('85), has described the veno-pericardiac 

 muscles as attached to the dorsal side of the longitudinal venous 

 sinus. The venous sinuses of Liniulns, as a rule, have no walls 

 substantial enough for a muscle attachment ; but posterior to 

 the second veno-pericardiac muscle the above-described mem- 

 brane is double and spans the venous sinus. Anterior to 

 this point the venous sinuses have no connection with the 

 membrane. 



10. Foramina. — Two pairs of foramina for the passage of 

 nerves have been found. One pair (/.i, Figs. 1-3) may be 

 seen at the bases of the latero-posterior processes, just out- 

 side the neural marginal ridge and appearing on the haemal 

 side of the plastron, a little posterior to the haemal processes. 

 These two foramina furnish passage for the intestinal branches 

 {in.n.^, Fig. 3) of the haemal nerves belonging to the sixth 

 thoracic neuromere. 



The second pair of foramina {f.~, Figs. 1-3) are located 

 in the posterior thinner portion of the plastron, near the bases 

 of the processes which form the occipital ring. Through these 

 pass the intestinal branches (in.nJ , Fig. 3) of the haemal nerves 

 of the chilarial neuromere. 



11. Relation of the Brain to the Plastron. — Following the 

 nomenclature adopted by Patten ('89, '93), the term "brain" 

 will be applied to the entire circumoesophageal collar; the 

 term "fore-brain" to the supraoesophageal portion, or the 

 part derived from the preoral lobes of the embryo; "hind- 

 brain " to the part formed by the fusion of the six thoracic 

 neuromeres ; and " accessory brain " to that portion formed 

 from the two abdominal neuromeres which fuse secondarily 

 with the thoracic neuromeres. 



