_Melalnikoff, S._ 1900 Zeit. Wiss. Zool. Bd. lxviii. _Herubel, A._ 1902 Sur le cerveux du Phascolosome. Ac. d. Paris, cxxiv. _Spengel, J. W._ 1912 Beitrage zur Kenntnis der Gephyren. Zeit. Wiss. Zool. Bd. xxxiv. _Ward, H. B._ 1891 Some points on the anatomy and history of Sipunculus nudus. Bull. Mus. Comp. Zool. Harvard College. (_Contribution from the Zoological Laboratory of Pomona College_) EXPLANATION OF FIGURES Figure 1. Central nervous system of Phascolosoma ×15. The cord is shown in three separate pieces. The lower end of the first or left-hand drawing should join with the second and so on. The central nerve band is shown with the lateral branches of muscle and nerve. The brain is shown attached to the first segment at the left. The pigment spots, cerebral tubes and chief nerves are shown. The brain is drawn from reconstructions made from serial sections. Figure 2. Cross section of the nerve cord. ×75. Figure 3. Longitudinal section of the nerve cord. ×75. Figures 4 to 6. Drawings of sections taken through the brain at various levels, only one-half is shown in each case. ×75. [Illustration: 1] [Illustration: 2] [Illustration: 3] [Illustration: 4] [Illustration: 5] [Illustration: 6] Littoral Ascidians Collected at Laguna Beach The specimens reported upon are from a collection made by P. A. Lichti during the summer of 1915, and from a small collection brought in during the summer of 1916. The determinations of all but the fifth were kindly made by Prof. W. E. Ritter. _Ascidia californica_ Ritter and Forsythe These simple forms were found quite abundantly under stones and in kelp holdfasts. The form of the body was determined largely by the position the animal took on the stone or seaweed. _Styela barnharti_ Ritter and Forsythe The specimens obtained were young, simple, of a redish-brown color and about 4 mm. high. They were found under stones at low tide but not as commonly as some others. _Styla montereyensis_ Dall A single specimen of this large, simple species was taken just off shore. It was slender at the base, expanded near the openings and of a redish-brown color. _Euherdmania claviformis_ Ritter This slender species was often found in clusters under stones. They were about 2 mm. in diameter and 10-20 mm. long, sometimes free from sand, at other times covered with sand grains. _Goodsiria dura_ Ritter