Larvae of Coquillettidia pertubans (Walker) are found in some marshes of permanent water with stands of aquatic vegetation. Eighty-six marshes, located within a 400-km2 area of Hennepin County, Minnesota, were examined in the fall of 1984 to determine factors that characterize C. perturbans breeding sites. We found that C. perturbans larvae attached to the roots of primarily Typha species although other plant species were also used. The water in sites with larvae was significantly deeper, lower in dissolved oxygen, and contained a significantly thicker layer of organic debris than sites without larvae. Larvae were associated with sites where Typha had specialized structures called water roots, which grow in the water column. Larvae inhabiting floating mats of vegetation were associated with interior openings within the mats.

For each $p$ in $[1, \infty)$ let ${\bf E}_p$ denote the closure of the region of holomorphy of the Ornstein–Uhlenbeck semigroup $\{{\cal H}_t : t >0\}$ on $L^p$ with respect to the Gaussian measure. Sharp weak type and strong type estimates are proved for the maximal operator $f \mapsto {{\cal H}^*}_pf=\sup\{\vert {\cal H}_zf\vert :z\in {\bf E}_p\}$ and for a class of related operators. As a consequence, a new and simpler proof of the weak type 1 estimate is given for the maximal operator associated to the Mehler kernel.

If the Poisson kernel of the unit disc is replaced by its square root, it is known that normalised Poisson integrals of Lp boundary functions converge almost everywhere at the boundary, along approach regions wider than the ordinary non-tangential cones. The sharp approach region, defined by means of a monotone function, increases with p. We make this picture complete by determining along which approach regions one has almost everywhere convergence for L∞ boundary functions.

It is shown that large (hundred-km diam) near-surface disks are capable of accurately representing the lunar mascons with very few parameters. While this does not ‘prove’ that the mascons are excess mass in disk form, it is highly suggestive. It is pointed out that virtually every proposed mascon theory is consistent with a disk shape for the excess mass. The tentative hypothesis is advanced that the mascons are, in fact, disk shaped mass excesses. The conditions for mascon formation and preservation are reviewed in the light of this hypothesis.